Before ours finally gave up and started leaking (about 11 years old – the vinyl perishes), i’d had it moved 3 times professionally.
I tried to do it myself once but without a decent pump and more importantly, the correct fittings for the bag, it was a nightmare.
I think the guy charged £150-£200 which included the full move and refill with conditioner.
We had a dual bag, dual heated, soft sided bed.
I did empty it myself when it developed a leak – this involved a lot of trips to the bath with a washing up bowl, until I could get the bag light enough to lift and empty in the bath. I then did the same with the second bag before ditching the whole thing.
The fortunate thing was that the soft sided bed had a catchment sheet underneath which meant nothing went through to the hard frame underneath.
We still use the base as our bed frame (and have a mattress on top), as it is basically a really heavy duty divan base with drawers.