I would look at both used and new, class A and class C. With your kids the ages they are, I would look for bunk beds - the fold out couches and dinettes often aren't big enough or comfortable for adults.
With your budget you should be able to find a decent used unit. However, with the steep discounts on new ones, and better financing rates for new units you may be surprised at what you can afford. We did not think we could swing a new MH and new car at the same time, but with our trade-ins, dealer discount and a great finance rate, we have the same monthly payment now as we did for a Tundra and travel trailer for our MH and Honda CR-V.
Take your time, and spend at least an hour in the ones you are seriously considering. Sit where you'll watch TV, stand where you'll cook, stand in the shower, sit on the commode, etc.
Have fun, and happy camping,
Elizabeth
2014 Thor Motor Coach ACE 30.1 (The Mothership)
2013 Honda CR-V (The Pod)