Ok, i understand what you're saying. That's kind of a hard situation. I can't say its a good idea for you to buy anything residential. That exmark would be the same as the toro, since they're basically the same mower. (same owners and all) Do you think you could sell you Husqvarna tractor for much, or did you want to keep it? Cause if you could get closer to the $5k price range, a whole bunch of mowers become an option for you. Also where are you thinking of getting this financing? Have you been per-approved yet? I recommend joining a small bank or credit union and seeing if you could get a small business loan. I'm not saying that you should get into more debt then you need to, or more then you can handle, but if that's what you need to keep things going and growing then it could make sense.
I know that someone mentioned it on here before, but have you considered the new 30" Toro Turfmaster? Its commercial. Comes with the amazing 6hp Kawasaki looks very heavy duty and professional, plus the cut quality is supposed to be amazing. I plan on demoing one soon, and if everything checks out, buy 2 of them for this coming season.
You could do the same. Financing both of them for just over $3k. Of coarse it could be a little slower then your tractor, but then you'd just have to keep an employee with for $8-10 an hour.
Toro 52" Z Master G3 (1)
Toro 36" Walk-behind (2)
Toro 21" Proline (5)
Walker MT EFI 48" GHS (1)
Hustler 42" Mini Z w/bagger (1)
Echo Trimmers, Blowers, & Saws
Hiniker and Cycle Country Plows