Are the bedlam quests bugged?

Solution 1:

The total value of the goods should be 500 (the raw value), not what the fences will pay.

Interestingly, if you do a sweep job in the same city, those items will count (and they're usually pretty valuable) even though you can't tell how much they're worth.

Here is a note from the UESP entry that may be of interest to you:

Note, stealing from the various NPCs and locations in the city may not work. Much of the time, to advance the quest, one must steal from the Keep of the the specified city, rather than its inhabitants.

As a last resort, if you are playing on the PC, you can finish it via this command:

setstage TGRNT 200

Solution 2:

Goods obtained from pickpocketing don't count toward the total of 500