is it ever okay to go with the only bid?

[Sam Burrell]

Hello! We just bought a place in a rural and extremely seasonal area but would like to get a bathroom in before we rent it (we already have renters lined up if the bath gets done). We have had a few contractors look at it and none have the time to do it in the next few months except one, whos quote was actually decent. 

He's licensed and insured and answered all the questions right, but we're leery of going with the only person in town who can do it with only one estimate to bargain. Better to wait or take the chance?