I have a three wheel bandsaw similar to the one above, made by Record (just a generic with a company name slapped on ) I've had it for 20 years and most days it gets used for not only the hobby but diy stuff as well. I've also got a scroll saw, bought two years ago and it never gets used, just a white elephant really. For the reason Ken gave above, I spent a whole day cutting scraps of timber and ply and plastic, even though I took time to set blade tension correctly I could never get it to follow cut lines ever!
As to blades, all you need to know is the length of the blade, then you can get them in a variety of tooth per inch and for cutting timber, ferrous and non ferrous metals and plastics from companies such as
http://uk.rs-online.com/web/ You can order online and delivery in 24 - 48 hours.
EDIT: I've just seen the homemade 3 wheel adaptation of a 2 wheel bandsaw above

mine is the same shape but the casing is actually a casting not sheet steel pop riveted into place