Hi sorry I haven't been around here for a little bit. Yeah well each manufacturer has a different serial number all together. The trick is finding the manufacturer sometimes, but usually in a serial number the higher the number the younger the instrument is.

And the way you can use a serial number is you can Google the manufacturer like I put Buescher serial numbers and then it was the second hit I think that had a list of the serial numbers. Once you get that look at the digits in the thousands place. Like if it says 98765, take 98 then go to the list and find where it fits within a production year. 

 Although a pawn shop is sort of like playing Russian roulette, you can't play it, just judge by the condition which even there may be misleading. Cosmetic is important to a point, a sax could look like it got ran over by a bus then someone grabs it and plays the most wicked blues song you ever heard. But you can either pick it up or ask to see it if they got it on a wall or something. Look at the pads, are the cracked or are the nice and smooth, push in the keys, make sure the action is smooth and see how fast they come back up, you want of course quick movements. Then from there inspect it, is there green crap on the places where the Bell connects into it, be aware of those and maybe look at other saxophones and pick one without green crap. Which is actually tarnish. 

 Also gently grab a pad and see if there's any play, there shouldn't be any or just a little. My Buescher has a small but of play on a key or two, but for a '78 saxophone its actually in good shape. But with any brand your looking at make sure you do research, especially checking where its was made. Like I said some horns that are cheapely made can't be serviced, so in a lot of respects you get what you pay for but there are good saxophones you can get for cheap. Just shop around, its a lot like buying a car except in my opinion saxosaxophones more fun. :)

And once you buy your sax if it's pawn shop purchase it wouldn't hurt to take it to a music shop and have their repair technician look over it. Usually if there's a problem you won't be able to get a note out as in there was a crack in one of pads you didn't see so its not completely sealing. Used saxophones from a music store aren't as much of a risk as a pawn shop find but they are more expensive. And also be careful if you think the guy is trying to rush you, that right there would throw up a red flag to me. But the stores I been to they are usually nice and even if you got half a million questions they answer them the best they can that was also where I found out that cheap Amazon saxophones can't be repaired. Then again there Yamaha saxophones on Amazon, Jupiter saxophones some decent brands, they are expensive 2-3 grand but that's what you expect buying a brand spanking new sax. Some professional alto saxophones can easily fetch 7-8 grand.

 But Buescher saxophones are good starters along with selmer saxophones and some old saxophones can fetch a few grand on their own such as a old '30's Buescher back when the difference between Buescher and Selmer was the brand both were great instruments but even my Buescher sounds nice and mine was after Buescher was bought by selmer and supposedly they weren't as good. And most important my sax can be serviced because i did my homework and stayed clear of the bad sax brands which music stores wouldnt carry a nonservicable instrument or subpar instruments. Yamaha saxophones are good as well if you got the money they hold value pretty good. The selmers you need to be careful with, Amazon sells them but I don't reccomend using Amazon, your better off going to a store. And as far as instrument type, its really personal preference, a student sax is good and cheaper than the intermediate or professional horns. At the same token if you buy a Prius you can't race a Corvette, however when you get good who says a Prius can't do doughnuts? ;) If you want a good horn and willing to spend the cash then sure get a intermediate model or whatever floats your boat. And like me if you want to give it a shot without putting your wallet in the ER, then just get a student model. 

Then again I absolutely love playing my alto sax. And oh my, I wrote a essay, whoops well I hope this helps with your sax hunt.