Someone posted on the Hybrid forum about an amazingly good $200 bike at Walmart a couple of days ago. Usually chain store bikes are deadly, but this is apparently a re-branded Specialized bike that normally costs around $400. You might want to go there and look for the thread or ask. Oh - and Walmart were giving a 30 day money back period or something like that.

Otherwise, an old rigid MTB with slicks can be a great choice.

General advice:

- Good 32 to 38mm tyres can be fast and comfortable

- If you have hills to deal, get a bike with a triple chainring.

That Walmart special aside, spending $250 to get a safe bike usually means buying used.