I buy my bootleg Lego mini-figures and block sets from only two online shopping platforms: Ebay and Aliexpress. Each site has it's pros and cons. I've pinned this post to the top of my blog so it's always accessible.
Mini-figures
Mini-figures can be bought individually, or in sets of 4, 6 or 8. I buy big figs individually. The best quality bootleg mini-figures are made by Sheng Yuan, Decool, Lele, Bozhi and Xinh. There are other Chinese brands but their quality is questionable.
Sheng Yuan sets, in general, are mostly eight figure sets, whereas Decool minifig sets have six figures in them, but sometimes there are more or less. I tend to focus mostly on the Marvel and DC Superhero mini-figures, but I have bought clones of the Lego mini-figure series, Clash of Clans and Ghostbuster figures too.
Block sets
Block sets can be bootlegs of older and newer Lego sets, or by Chinese brands such as Sluban, Enlighten, Ausini and Bozhi. Examples of Lego sets can be older city vehicles or more recently, buildings from the Friends series, or Superheroes vehicles.
Sluban makes a few airplane and city vehicle sets. Enlighten sets clones some of the older Lego sets like submarines and trains. Ausini makes their own train series that Lego has not produced.
The latest block company to enter the foray is Lepin. They have successfully cloned all of the Lego modular buildings and several of the large Star Wars sets.
Ebay
You can usually find mini figures and block sets under the Toys and Hobbies category. Most times they are in the Building Blocks subcategory but you can also find them in the Action Figures subcategory.
Items are listed in auction format or Buy it Now. I look for items that come with Free Shipping where the sellers are from China. Sometimes you can find some really good deals with Buy It Now, but the best prices come from winning an auction and paying a lot less.
For Ebay, you'll need a Paypal account to provide the most painless payment method.
I have found that sellers typically ship out the items within one or two days of payment and it takes on average three weeks to one month before I get it.
Items will come with a tracking number (see below for more about tracking) and an estimated delivery date. If the item doesn't arrive within the specified period, you can get a refund from ebay.
Aliexpress
I've been using Aliexpress since early 2014. Aliexpress is like an online mall where many sellers have virtual storefronts. You are basically dealing with a seller and not Aliexpress directly, although they will try to mediate disputes. There's no auction style listings, only fixed price listings. Some listings will state a minimum quantity that needs to be purchased, because they might sell both retail and wholesale.
Some items will be shipped for free and others will charge for extra shipping. I don't know why but it takes up to one week for a seller to ship an item, and then it takes over one month for it to arrive. if it takes longer than one month, raise a dispute with Aliexpress.
It's somewhat intimidating for new users because of the plethora of products available. There's a learning curve to figure out how to filter out the items you are looking for. Start by browsing the Blocks category and use the search filters to find things you are looking for.
Be warned that seller ratings and feedback are irrelevant. Do not trust any of the feedback or reviews because they may be bogus. Even sellers with great ratings will still try to scam you. You have to understand that it's buyer beware and ethical behaviour is not always followed on Aliexpress.
You may discover some amazing deals, but even though they are listed, the seller might not actually have any stock. I have bought items only to find out that the seller lied about having inventory. Sometimes they will give you a fake tracking number and indicated that they shipped it when in fact they didn't.
There is no requirement for a seller to honour an item's price. They might decide not to sell you the item because they realized they priced it too low. Sometimes they try to ask you for more money after you have bought. If that happens raise a dispute right away. I tried to file an Aliexpress complaint against the seller, but there are limited complaint categories and if it isn't listed, they will not listen to your complaint. Seller asking for more money after an item purchase is not considered as fraudulent by Aliexpress.
Your only recourse is to get a refund but you will have to raise a dispute and wait sometimes up to one month to get your money back.
Paypal is not an option for Aliexpress users. I have purchase protection on my Visa card so I use this as my payment option.
Tracking
Most items come with a tracking number but there are two types, one for small packages and one for larger packages.
Small packages are usually sets of mini-figures or items under ten dollars. The tracking numbers associated with these items consist of ten numeric digits.
I use this website to track packages originating from China.
http://www.trackingmore.com/
Larger packages come with a different format tracking number, ie:
RI586779712CN.
The first letter will always be R and the last two letters will be CN, sometimes SG or HK. The last number is a check digit to verify the other numbers in the tracking number.
If you suspect that the ebay or aliexpress seller gave you a fake tracking number, you can check to see if it is valid at this website:
http://post-tracking.com/validate/
Hope this information has been useful to you.