i would suggest a 3000 or 1200
a 3000 has a built in scan doubler and flicker fixer (search this site for people begging for sd/ff for other models) and it can take zorro3 cards and most 4000 accelerators. a base model can do mod stuff really well and accellerated with a sound card can do that and mp3 and sampled stuff as well. 3000's also have a very decent scsi harddrive setup.
a 1200 has lots of accelerator and memory options available as well as probably the best tv ready signal out on its composite connector. it has an ide hd connector and comes with os 3.0 kickstart at least so you most likely wont have to upgrade that.
amigakit has 1200 setups to order at really good prices or either can be bought on ebay for not too much. i got a 1200 on ebay with ram card for 120us and ive seen 3000s for around there
250us will get you a decent setup for most models except for 3000t, 4000, or 4000t for those you would neet quite a bit more.
if you get a 2000 you would probably want an accelerator and ram and hd card right off the bat as well as a multisync monitor or flickerfixer or an card with composite out (not an a520 they suck from what i hear)