My Mother once bought a travel cot on ebay and so I decided to sell them, but the simple things you need to know when purchasing a Travel Cot are:
Easy: It's easy to assemble and fold back, after all you want it to fit in your car or into a small space. This is after all a temporary cot that you will want to store away too.
Fabric: This made from Nylon and is easy wipe it clean. After all if you're travelling you may not have a washing machine to hand.
Carry Bag: An absolute essential, this will stop the whole thing falling open when transporting in the car, and easy for storing when at home.
Adjustable height: If you have a little one that can't sit or stand up on their own yet, you may want to ensure you travel cot has either a zip opening at the end so you can pop your baby in through the mesh whilst bending safely, or that it has a bassinet (not all tavel cots have these, they are like a raised platform that adjusts the height of your travel cot mattress), so that you can have it at the top level when you're child's a newborn; and use the lowest level when you're child isn't safe to leave at that height (i.e. when they start to sit up/crawl).
Guarantee: You wouldn't expect anything different on the Highstreet so why put up with it on eBay?
Good Policies: Check out seller's policies as businesses must allow you a 7 day cancellation/7 day return, in accordance with the Distance Selling Regulations.
Price: Why pay High Street Prices when you can buy cheaper on eBay?
Why not check out my shop: Bizi Baby for your travel cot requirements. If you quote this guide I'll offer you a discount!