well, if you have a high tolerance to benzos (like i do), try getting your hands on some pregabalin or gabapentin. pregabalin is better, but gabapentin works too, as they both significantly potentiate benzodiazepines. a good starting dose for pregabalin would be 150-600mgs (some people get pretty good results with a low dosage). gabapentin i'd say 600-1200mgs as a starting dose.
if these dosages are too high, someone correct me if i'm wrong. i get pregabalin prescribed, and it's been useful on its own as a mild anxiolytic, (not that recreational) but it has been incredibly useful combined with other drugs. almost every drug i mixed it with, it enhanced the high. if you're starting out, i'd recommend taking not much more than 300mg the first time just to test the waters and keep the benzo dosage low. generally gabapentin and pregabalin are not hard to get prescribed, if you know what to say to the doc.
edit: for me mirtazapine works really well as an hypnotic. i've been taking it for four months, and aside from a little weight gain it has virtually no side effects. it doesn't lose its effectiveness over time, and a small dose will still make me sleep like a stone. benzos are pretty shitty for sleep in any case, their best use is as an anxiolytic, but only if not taken more than once a week.