I have coworkers that fly on Allegiant regularly between BLI to LAS. They think Allegiant is good value and don't have any complaints.
I haven't flown on them myself yet but have looked at them a few times (rather fly out locally versus having to deal with crossing the border). Be aware of the miscellaneous costs such as the booking fee and the checked luggage fee (cost per item in BOTH directions). From some reviews I've read, the service/experience on some routes are better/worse than others.