Ok so, had a few guildies with this problem and figured i should share this trick i found with whoever else needs it.
If the sorting is bugging and gets screwey after you change pages, do the following:
If you want to browse items by cost:
Hit refresh, click on cost (to sort) THEN offer THEN cost again and you're ready to browse all pages alphabetically (beers, bread etc)
If you want to browse items by offer:
Hit refresh again, click on offer THEN cost THEN offer again and you're free to change pages.
Hope this helps,
/Mak