Well, that's right... I know there's AV as close as in Sweden, and it costs 1200€ per vial (~1500 USD), but it's also hard to get. A lot of red tape etc.
So, as you can gather, I do not possess AV for Boomers. Naturally I don't support the thought of getting venomous snakes without the AV, but like you said it's expensive and difficult to get. Honestly speaking, I don't have AV for any venomous snake I keep.
But I also believe in the individual's right to choose. The only one at risk -so to speak- is me, I have taken precautions that no-one else will be at risk.
I believe there are people out there who'd like to lecture me on this one, but I have thought this through a lot of times before I ever got my first hot.
Besides, unless I'm completely wrong, in the case of a Boomslang bite, a blood transfusion may be required even with the use of AV. (Somebody wiser please correct me if I'm making things up here.)
Which is not to say that I'd put my faith in something like that. I do my best to not get bitten.
Having said that, I have to say once again, that Boomslangs are one of the most interesting snakes I've ever had the chance to work with. Save for one, all of my other individuals are quite easy-going.
All the best.