Phenibut apparently doesn't seem to work when taken constantly: after a couple of weeks, the effects diminish. But, that is just what I've read; information I found on here when looking for similar solutions to the benzodiazepine problem. I'd recommend it for benzodiazepine withdrawal, though it works in a similar way, so ultimately you're trading addictions and anything that works similarly to benzodiazepines is likely to involve a similarly desperately-painful struggle for reality and normalcy through the dark recesses of your soul, and ultimately, bah, is it all worth it?
I'd advise against using butalbital: it's a weak barbiturate, but yeah, it's a barbiturate, and those are dangerous relics of a bygone age where a fervent desire to finally rest could end up with you sleeping and then never waking up!
There are certain 'Research Chemical' benzodiazepines available online, but in the first place, I think you've been given the wrong drug: don't just write this off, 'cause see, you're being given something that lasts about 1-2 hours and being told to take it four times each day, rather than just, say, 1mg clonazepam (Klonopin) in the mornings. Is there any reason for this? Just, you could take a Xanax several times a day and go through ups and downs of panic, or take one pill and be ready for anything throughout the whole day! Diazepam is still very effective and works wonders, as much as it did in the 1960's.
Why don't you drink? Alcohol is the clear choice here: it's easy to obtain in large amounts and allowed by everyone despite its dangerous and toxic nature. Take a shot of vodka—not cheap stuff, mind you—every time you feel the onset of withdrawal, not panic, and it will help you sleep, help relax your muscles and help with all sorts of other nonsense. You having been on this for two years is really a shame: the tapering requires time and plenty of diazepam, or some similarly long-lasting benzodiazepine with a long half-life to help get you down to 0mg, and alprazolam is really bad for this.
I say: see a doctor and ask them for a taper, rather than a short-acting benzo' you're forced to take multiple times a day just to keep it in your body and working on your anxiety, get on diazepam or clonazepam or something that'll require just a single dose that can be dropped via decrements of 2mg, until finally you're on your own and maybe a little anxious, still, but not leashed to a doctor and pharmacy and drug for the rest of your remaining years.