It depends on where you are and the trends. TBs are athletic and can lend themselves well in most any english discipline... but like said, they're a dime a dozen and most people who may take on a green TB may really be inclined to look at a straight OTTB. However, Warmbloods are becoming readily available and trendy... because they're less reactive, they tend to attract your Amateur riders more than a TB.
What you need to consider is your local market... do you have an area where people are competing heavily in english discipline events? Are they mostly local level or upper level? Are you conveniently located?
Where I am, there is mostly small shows where the horses are just well trained trail horses, retired pros, or experienced riders getting a green horse ready without losing it's eligibility. We also have 3 tracks in a 2 hr drive, so TBs are nearly as common as the QH. Big venues however are at least a 2 hr drive, as are the major metro areas. Though I show eventing and would love to flip TBs for that purpose... economically a good trail horse with some rings skills is what sells around here. I still advertise them further south and have sold horses there, but it's harder... takes coordinating on my and their ends.
As for costs.... 1000 doesn't cover much over a 70 day time period unless you have your own farm. If you're boarding or renting, you need to consider that in your costs.
Start small and build your reputation. You will need to network, know who to call when you have a particular horse in your hands, and have a niche. For example, people come to me when they're looking for a good athletic trail horse. I don't have time to buy and sell right now, but I still haunt sales and know people I'd call... you need to be one of those people (figuratively speaking).
If your horse says no, you either asked the wrong question or asked the question wrong
And God took a handful of southerly wind, blew His breath over it and created the horse