"Plan 9 From Outer Space"
General regarded as the worst SF film ever made, here's the synopsis
It's all here, the not-so-special efects, aliens in skating skirts zooming around in string-powered flying saucers to implement the ninth plan of earth's conquest (the first eight failed) with an army of zombiess (well, three actually): Vampira, Tor Johnso and Bela Lugosi in his legendary "postmortem" performance (with Ed's chiropractor standing in for Bela after his death).
I just had to buy it for $2.95 from the clearance sale at EzyDVD.
http://www.ezydvd.com.au/promo_large.zml?pid=383
I also got years 1 and 2 of "Space 1999"