Yep, there is an easy way.
Go through the deal of buying it, and just before you hand over the cash, ask for their help, be prepared to pay for it though.
They'll want to sell the tank and I'm sure that would work if you said
"No help. No tank. I'll go and check out the other LFS"
Also I use old safety straps from cars, (get them cheap at the wreckers),
for the lifting of heavy tanks, and the grandchildrens skate boards make an ideal trolley
Use planks or 12 x 1's to come up stairs, and once inside, use a large towel or a rug to slide it on the floor,
remember to put the bottom of the rug to the base of the tank.
I know not every house has them, but saw horses make an ideal resting place, before finally going onto the stand.
Just some things that I use for moving some of my biggun's around on my own.
Alan 104