pddufrene, I'm in your boat.
Burned my old BIC 10" sub amp out. Polk PSW505 caught my eye at Amazon for $189, then they increased it to $249. I started looking at the $300 price point, did a lot of reading and found out how crummy the budget subs really are (and since I had a crummy one, the descriptions resonated with me!). Really liked the $500 price point of the PB-1000, and decided to see what else was in the neighborhood. Thought of one PB-1000 now and another later. Aw, maybe I want a 12 inch. Price point keeps going up! $550, $650, $750.... It's easy to get enthralled with the features and low, low, low response. For me, the PB-1000 would KILL what I had before - and I was pretty happy with it 'til the amp fried. So despite all the push recommending spending just a little bit more, I know what you mean about having to hold on your budget amount. There's always something just a little bit better, for just a little bit more (usually defined in $100 chunks!)
I'm not pulling the trigger on something a lot more expensive myself without realigning a few things, but decided I don't want to get a sub that's really good - only to know in the back of my mind I want to upgrade later. So I decided to adjust the budget accordingly. I know the PB-1000 would be a great sub for me but I don't have the room for a pair, so I decided to get something larger and stick with one unit instead. I'm going through bass withdrawal - several weeks now - but I'm holding out for the best thing I would be happy to spend on. As for sales and stuff - can't do anything about that timing, when the budget allows, I will price everything then and make my final selection.
My current faves, in no particular order are: HSU VTF-2 MK4, Outlaw LFM-1 EX, Rythmik LV-12R, SVS PB12NSD and PC12-NSD.
To me, those are the next step up from the $500 price point. Good luck to you and take your time analyzing!
PS: to all the posters here at Audioholics - thanks for all the great info! It's actually a bit fun not being able to lay out the credit card yet, and having all this time to analyze what I think would sound best for me. All the reviews and comments are really helpful, whether experience or opinion!