Cheap sub amplifier

Hey all, I currently run my 4*1850's (800W @ 8ohms) on a QSC MX3000a which is slightly under powered for the job. I don't have much of a budget and am in Australia just to make things that bit harder.

Options i think are either

1. get another MX and bridge them however this would then massively overpower and I'd be scared i'd pop a driver, especially since they are loaded with Chinese Ande drivers.

2. sell my MX and try get an amp that would do all 4 (however i'm limited in terms of power draw as often will be running in places where 3phase power is not avaliable)

3. sell the MX and buy 2 more suitable smaller amps to be bridged.

I'm leaning towards 1 or 3 however if anyone has any great suggestions for powerful cheap (second hand) amplifiers that don't require a large amount amps to power them i would love to hear from you.

If 3 is the way to go what are people suggestions, keeping in mind cost and the fact that they will be powering subs.

Thanks in advance