Nine times out of ten if you have to ask if you did alright in a deal, then you didn't do very well. I'm not saying you lost out here, but you did do this backwards.
Let's focus on the finer points of getting a good deal. This may not all apply to your situation, but maybe those that are reading it will obtain some level of better judgement skill in the future.
Research: This is the most important thing to consider here. If you don't know anything about what you're buying, then how can you make a determination of whether it's outdated, crap, great, or cutting edge? The answer is that without prior knowledge it won't just "come to you".
Understand the Seller: "What does he mean 'Understand the Seller'?" I mean you need to know what the seller is up to. If it's an ebay purchase you should check feedback, quality of listing, pride of ownership, etc... If buying off a stranger locally, talk to the person, make sure they're legitimate owners of the items you're buying.
Test the product: This goes in line with understanding the seller, especially when dealling locally. Something could be faulty and the seller may be either unaware or will avoid disclosing a problem to you. Fully test any and all parts you can. If the seller is not willing to facilitate a test, move along.
If there are any points I didn't hit on, someone chime in. It's late and I may have forgotten something.
