Alpenlite was a premier trailer builder when they were in Production. Sadly there were many reasons for their demise. Personally i would not hesitate to buy one even today. Remember appliances and equipment are the same as other less costly trailers so parts and service will be still available.
I don't remember what year they switched from in House to Lippert frames, but I believe it was around 2004/05 time frame. Might have been as late as 2006. Have you done a search for the WRV club? I think they are still active on facebook or somewhere similar.
My favorite floor plan was always he Augusta.