same experience ( 8 years of vb3, then vb4), I didn't want to "upgrade" from latest vb4 to vb5...
XF is nice , with huge quality, even if it's not perfect of course...
BUT one of the main problem, is , as you noticed, the difficulty ( cost +++) of purchasing addons (there are other problems of course )
I really miss something like vb org...so much really nice people, experimented coders, perfect addons and so much choices.... FREE... with ( yes it's true) free updates/upgrades! nothing like this here... 
here I discovered addons which (most of them) aren't free ( some VERY expensive), with subscription system (!!!! again more money!), the final cost is finally huge if you want to get some, and keep them updated after a few months!
take care of your wallet!
I don't know why there's this difference about $ for addons ( vb vs xf)....
Is XF more used by large forums, with money income (ads, membership ?)..... but middle size /free forum, without ads , can't afford lots of addons..
just my 2 cents !
