There is a company in Yucaipa, CA that reconditions and sells Rialtas and Eurovans called Rialta Heaven/Pop-Top Heaven. Their website is www.poptopheaven.com
. They currently list a 2005 Rialta Double in their inventory.
Otherwise there is Bill's 2003 Rialta "Full" (probably a Double) in the previous post. Winnebago called the Full bed model a "Double". And then there is searching and checking eBay, Craigslist and the various internet Used RV sites. Good luck.