If you look at The last but one issue of StW they review an Islabke with Vs and thought it not bad. If its all you can afford it will get you out on the trails. Most disc brakes are better than Vs but some are barely any better.
I did the Ported du Soliel on a disc front and v rear braked bike in 2000 and survived. I also survived the entire MTB era before V brakes. But ask me to forego disc brakes now and I'd tell you to go take a leap