FN-49's come up regularly in the EE. Lately they seem to be in the $450-600 range.
SVT's seem to be in the $500-600 range. Stock M305's are cheaper and AG42B's probably the least expensive.
If you're looking for a cheap(ish) plinker, I'd go with the SVT. 7.62x54R is probably the cheapest milsurp full power cartridge available right now.
If you want a rifle to modify and tart up, go with the M305.
I've got a 8mm FN-49 and definitely prefer it to my SVT. Not saying it's better, just that I like it more.
If you're just looking for a cheap centrefire blaster, have you considered an SKS? That's the least expensive of any centrefire semi to purchase and feed.
Ideally you would find someone who owned some of these so you could try them out and go with what you like the most.