Its difficult to say what your budget should be. I was in your exact same situation when I first purchased a bandsaw. I walked into woodcraft with $400, I spoke to a salesman who told me what I needed was a 14" and pointed to a $1,200 rinkon. I told him I couldn't justify spending that much on it and left with a $375 9" 1/3 hp Jet. At first I was happy with the jet and it seemed to preform better than he had let on but it wasn't long before I started to realize it's shortcomings. I wasn't even to the level of resawing, just ripping 2x4s and it would bog down. Learning that I purchased a craigs list 14" 1/2 hp for $100. Trouble with it was the previous owner saw fit to remove all the brand identifying decals making spare parts a no go. After spending hundreds more to get it to work but still not work well I got fed up and got a good one. I will point out that I don't have a table saw. I went for the nice Laguna with the understanding that it would be my table saw, but also handle resawing and curved cuts. I use mostly reclaimed lumber and rough cut stuff from some guy out in the woods with a portable saw mill so I resaw more than anything else... but thats just me. If you have a nice table saw and use mostly precut stock a 14" 1/2 to 1 hp would probably do you fine.
If cost is your biggest worry keep an eye on craigs list. It may take a while to find a good one and you will probably have to travel to get it. From my experience the biggest thing to consider when buying a used one is be 100% sure you can easily find parts because you will have to buy something. There are aftermarket parts from companies like Carter Products but a few parts will cost more than any 2nd hand saw.
Another thing to consider is having more than one saw. Changing blades is annoying even with quick release. My numerous missteps have left me with a 1/2 hp 14" that I'd like to equip with a 1/4" blade and use for curved cuts on thin stock and leave my 3/4" 3 tpi blade in my beefy Laguna for resawing and working thick stock. That being said this band saw trouble has caused me to ask one question when I buy any tool... "will this be the last one of this tool I will ever need" if its "no" I don't buy it becuase you will spend more buying any two machines than any one.
as far as craftsman goes, I have never worked with one but have heard they are bad about just not making parts for older machines, and they are not known for having parts available through 3rd party venders.
