While travelling last year, I had planned to head to CM , but opted to head to Bali instead. Like Conni (who was at the Dojo around the same time as me, hi), I stayed in Canggu due to the surfing (didn't even bother checking Ubud . If that's something you want to pick up, then Bali is the place. If you just want a nice beach, you should probably stay in Thailand and head to Koh Lanta or some other island. Tourist visas in Indonesia only last 2 months, so you'll have to do some frequent visa runs or change the status if your plan is to stay there long term.
I was able to find a crappy room in Canggu for 150usd/month, 600 meters from the beach (and 300 meters from the Dojo). It'll be very hard to find a room in a villa w/pool for 250usd, but I don't think it's impossible. I'd say that you'll have to share the villa with other people though.
I was spending around 600-700 usd/month in Bali, between the room, coworking, food (always ate out), board rental, bike (you can bring the price down a lot if you negotiate a long term rental, don't be surprised by the initial asking prices). I wasn't partying though (but it definitely looked like a great place to be single...)