Allow me to recommend The Golden Age of Science Fiction series by Halcyon Press
http://www.amazon.com/s/ref=nb_sb_no...tion&x=15&y=20
Many, many wonderful stories from the 1930-1960s, including short stories, novellas, and novels. I thought I was well read in the field until I found these.
At $2 a pop for 50 stories it really can't be beat, although many of the stories are available free this series brings them all together in single volumes. There are twelve volumes of short/novella anthologies and at least a couple of novel anthologies.
Another very classic and, at the same time, new series is the Solar Clipper Trader Tales by Nathan Lowell. Two volumes are available at Amazon and elsewhere at around $5 and he has many more in the pipeline.
Edit: Quarter Share and Half Share are now out, Full Share is coming out in the next couple of months.
http://solarclipper.com/