Getting back to the original post...
Is it really a small tractor you need or would a larger ride on mower work for you? especially as collecting the grass and shredding cuttings is mentioned a few times. I'm happy to be corrected but if you want a tractor attachment that will both cut the grass and lift the cuttings...that could be an expensive piece of kit. And then you need a tractor powerful enough to use it.
Would another alternative be - dont buy anything and get someone in periodically to do the work? Not as much fun as you dont have a new toy to play with but it would be cheaper in the short term.
When I first got my smallholding I bought a small second/third hand Kubota (24Hp) which has been pretty bullet proof. The only problems I've had have been of my own making due to ignorance and/or lack of mechanical knowledge. It came with a topper and a flail mower which have been great but they wont lift the grass.
I would also have suggested getting in some four legged woolly mowers, the initial purchase costs wont be as high, service costs are typically a lot lower and best of all they wont leave any cuttings behind. The catch is it can be a real pain trying to empty into the compost bins
If you still think buying something is the way to go, it might be worth speaking to someone in the local councils park maintenace dept, landscaping companies to see what they do with old stock or if they know of anyone that might be selling up.
Cuddles