Amazon is pretty good for finding used games for most older consoles, the Master System included. There are often a number of games, accessories, and systems for sale, though sadly at steep prices. If you're looking to nab some commons at decent prices, it's a good place to start, but be careful about buying boxed systems or more complete items, because you'll be paying quite a bit of money to do it. Either way, you can check out their site. It's definitely reputable, and you usually won't have any problems with your items' shipment, so at least it's safe.

Run by an occasional drop-in you'll sometimes see in the forum, Blue Rose is a website with a fairly good selection of games, consoles and accessories for sale. He's based in the USA. Check out his website here.

This is currently the most well-known, privately owned video game auction website on the internet. Created as a way for gamers to buy and sell games without dealing with eBay, it's pretty popular and you can often find a good number of Master System items there now, as well as some pretty high-profile auctions now and then. Some sellers have recently been making various SMS reproductions and selling them on the site. Regardless, it's another good auction site to check out, so do so right here.

Over the years, Craigslist has grown into a site where anyone can post nearly anything for sale without cost. Sometimes you might come across some shady listings, so be careful, but you'd be surprised how many good items you can find at really cheap prices. They have postings in many countries now, all over the world. Visit their website to see what you can find. It's hit or miss and you have to stay on it to find anything good, but now and then you may be surprised.

Dawdle is a fairly new video game trading site that is, as they say, "for games, by gamers". Their Master System selection is fairly small at present, and they don't have much, but in time it could grow to be a good source to use to increase your collection. Check them out here.

Depending on your location www.ebay.co.uk or www.ebay.com are the perfect places to find Sega Master System treasures without having to leave the comfort of your home. Prices are usually very reasonable, although people to tend to put out silly money for rarer games. But, it is still currently the website to go for if you're looking to complete your collection. Rare items appear on here more than anywhere else. Hundreds of Master System items are listed daily in countries all over the world. Prices can sometimes go high depending on who's bidding, but most of us have only been able to complete our collections by using it. And when you get into Japanese titles, it's really the only way to get them complete.

An enigma to some, an abyss to others, Mercado Livre is really the only way you're going to be able to get Brazilian Master System games anymore. There are hundreds of listings all the time, and since Brazil is the location where the Master System was going strong until almost 2000, you can expect to find a ton of items. The problem is, good luck finding a seller that will use Paypal or ship out of Brazil. Whatever you do, be careful, don't send cash! If you're worried you can talk to sellers and maybe even find a contact to use for finding items you might need. Either way, drool a bit and check it out.

A nice little site if you're looking to nab some Mark III titles for your collection. They're usually loose, but that's not necessarily a bad thing. Easy to navigate as well, so check it out.

Located in the UK and France, Price Minister is a site similar to Amazon in a way, but catering mainly to technology, including video games. You can find some Master System items there from time to time, but don't get too excited.

Don't kill us for putting this here. Like it or not, Telegames is a pretty well-known, UK-based, used video game seller online. Keep in mind, though, that they're mostly well-known for saying they have stuff in stock that they haven't had in months. However, because of this, you can sometimes come across some great stuff on the site because no one wants to touch them. Be careful, they're known for listing items they don't have. Some sneaky members have used this to their advantage, and on one occasion someone actually purchased a complete, sealed Lucky Dime Caper Gift Set for 45 pounds. Check before you buy, but you never know what you may find.

Here's a nice catch-all to finish off our list. We could have put a number of other sites on here, but the above list includes the most well-known. What you have here is an online database that keeps track of sites that sell Master System items (as well as plenty of other systems if you're interested). Most of the sites are US-based, but you'll find some European stores in there, including Germany. If you're tired of the above, go here.