A new tube for a 28" (100Hz type 8300) avant is around 550,- (B&O price) so i think 1500,- for replacing a 32" seems rather 'overpriced', try inquiring at B&O Netherlands, Naarden (if they still exist: i remember them as good, friendly and honest people) also for a price.
To my knowledge there isn't any cheap replacement type, i've been looking for these (for 50 Hz T8111 and T8300) but it seems like the ones used in the Avant were designed for B&O, although indeed other type of Philips tubes seem to be sold for 150,- to 200,- but B&O still charges (actually increased the price last year...) sky-high prices for the tube.
Replacing isn't all that much work, a couple of hours and some proper space :).
For the mentioned 1500,- i'd say: go for a RF avant !! (maybe try a good trade in at a dealer, your broken Avant on a RF type, these days you must be able to make a nice deal....).