I found that the few flatbed scanners with transparency unit large enough to cover 8x10" are in the $500 plus price range.
I finally managed to locate one in my price range, a used Epson 1680 for $70 on eBay.
It's a professional graphic arts model sold for years and still supported, including drivers for modern OS's.
Though good in its day resolution and Dmax of this model are a little below top modern flatbeds.
However it should suffice for the purpose intended, i.e. scanning album pages of my 35mm rolls.
Chris