Charlie, if you do go the "buy my own" route, as others have said, rental is the killer. I dealt with BOC for many decades, but in the end their prices got to high to continue. I now use Bunnings gas for oxy, acetylene and argon. I pay a once only $200.00 per bottle with no annual rental. The re-fills are cheaper than any other supplier and when you are finished with them, simply hand them back and get the $200 refunded.
I might add that after closing my BOC account, they offered me free rental for the first twelve months, if I re signed with them. Trouble is, after the first year, you are back on their tread mill.
As for straightening the pipes on your gates, a method we used to use on stainless bow rails on launches was to get a length of 4 x 2 about 3 feet long and attach a small block of timber to each end which had a groove to match the diameter of the pipe. This was placed on the pipe on the outward side of the bend and another block with the same groove placed opposite. We then used a large "G" cramp to squeeze the two pieces toward each other, thereby gently straightening the pipe without risk of further damage. Yes, I know Sunshine gates are made of good stuff, so you may need a bit of heat to help it along.
Cheers, Steve.