It is easier if you can tilt the cab but you can remove them without doing that. In my younger days that is the way I would do it. I can not comment on the quote you received because I do not know what you told them. While we all like to know what a repair will cost it is impossible to do so accurately everytime. My father would not give estimates because as he said, somebody is going to get screwed. If he made it to low he would get the short end and if he made it to high the customer got the short end.
The seals and hydraulic pump seal kit should be less then 200.00 I think. You do not need to disassemble the hydro pumps to replace the seals.
To remove the pumps you will need to raise the loader and block it under the frame, not the wheels. remove the plate in the middle of the underside of the loader. You can drain the hydraulic oil by removing the engine access panel under the engine. Remove all the lines and disconnect the linkage to the pump levers. I can not remember if you will need to remove the center neutralizing support. If you do it is just a matter of removeing the bolts from the handles to the shock and linkage. There are four bolts that hold the support in place. There are two bolts that hold the pump to the engine gearbox. The lower one must be accessed from under the loader.
Once the pumps are out you will need to remove the snaprings holding the gears to the pump shaft. There is then a snapring in the end of the pump housing holding the seal in place. Remove the snapring and pry the seal out being careful not to damage the shaft. You can take a small drill bit and drill a hole in the seal and screw a srcew into the hole and pry the seal out. When you install the new seal you need to make sure the lip does not fold under as you install it because the sealing surface of the shaft only slightly protrudes past the pump housing. A small screw driver will help work the lip over the shaft. The seal will drive in and install the snapring, the gear and its retianing rings. Try not to use a punch to install the seal but a piece of pipe the right diameter. Be sure the thrust bearing and bearing races and the spacer ring are installed before you install the seal.