First, I'd double check that it isn't a torsion axle as already mentioned.
Second, if the price is right, and you go very slow, you will be just fine getting the tractor home and then you can use the trailer for other stuff.
We have biult ourselvs 3 homemade trailers over the last 6-8 years. They were built for the sole purpose of hauling firewood. And all of them were build with steel we already had and old 3/4 ton truck axles welded solid. This gave us as low a deck height as possible. They also have 35x12.5R16.5 tires on them. This helps them roll easy and cushion the load. They tow just fine up to 25mph which is how fast dads 8n with the sherman will go on the road. This is empty @ about 2500lbs or loaded with 3/4 cord of wood @ ~4k more.
We have also huled a ZTR mower on the one trailer about 10miles. Didn't go over 35MPH and it was fine.
So it all depends on the roas you will be towing on, and if you have anything you can use the trailer for in the furure like hauling wood. If it is out in the sticks with some really rough roads I'd pass. But if the roads are smooth, and you can get good use out of the trailer in the future, and the price is right, why not.