LOL! I've thought of selling mine due to a lack of use(I use the Gitzo more) but then if I sell it I know I'll miss it
I not for the hassles of carrying two tripods, I'd use it alongside the Gitzo, but it's really only a wide angle lens type tripod .. too flimsy(as in not rigid, not in a durability sense) for longer focal length lenses or macro.
With ballheads, my thinking is that bigger is better. We all obviously have size/weight/price constraints to consider, but if you have a set price to adhere too then whatever manufacturer you choose, just try to get the biggest ballhead you can afford in their range.
If you use that $600 upper limit as a more realistic guide, then I think a mid sized set of legs, with a larger than normal(ie. 45-55mm ball size) ballhead should be fine.
From memory that 17TSE is a large lens, and a bit front heavy. Maybe not as much as a 70-200/2.8, but that large front element makes it feel more front heavy than a regular 17mm lens otherwise would.
At 17mm for architecture you're not really reliant on absolute stability/rigidity .. magnification isn't going to be an issue in terms of small vibration problems. This is an issue with 200-ish and longer focal lengths.
So the rigidity of the legs don't have to be absolutely perfect. hang a bag on the centre hook to shift the weight of the setup lower and change the weight ratio of the camera/lens combo relative to the support system.
Better rigidity is had if the support system has more mass than the gear it's supporting
So with that in mind, you can get away with a mid sized tripod and if any issues arise in terms of vibration(eg. due to strong winds if outdoors), then the bag hanging routine helps massively to stabilise the setup.
BUT! the ballhead has to counter the weight of the lens, and that's hard to account for in other ways.
That is if the lens is dragging the head downwards, you can't really do much about that like you can with the bag hanging trick for the legs!
There are workarounds for the sagging head issue, that involve multiple plates of different lengths and suchlike where you slide the camera/lens combo back a bit on the head to shift that weight rearwards.
So I'd say a mid sized tripod(circa $200-400) depending on the feature set you want and material used to make it .. but get a larger $200-400 ballhead.
The way I'd approach your specific situation would be to work out the ballhead first(ie. it's cost) and then use the balance of your budget to get the tripod up to a satisfactory quality level.
THIS ballhead stuck out like a sore thumb when I came across it on ebay while buying a couple of lenses a while ago.
I can verify the seller as I bought two lenses from them and they came in a day and half(Syd to Melb). I can't verify the actual product, BUT!! .. its a direct ripoff of the RRS BH-55(which I have).
if it works only half as good as the RRS is supposed too, then I think it comes across as a bargain.
I think the No 1 pro for the BH-55 is the very low profile design. There is an issue that I have with it, but that's probably not going to be relevant for your usage(ie. wide angle situations).
That LH-55 could be a solution. A bit close to the high end for your budget, but I reckon you could get a good tripod for 250-300 to match it too.
I'm thinking of getting one to compare to my RRS head .. just for a laugh!