Thats a great question. Save a space elevator, the only way i can see to pull of -$500 would be a horizontal take off and landing space plane, probably ramjet. but once we hit that point, He3 mining could really start to hit big on the moon, but without the drop to at least $1000, you can't do it privately, Ive done the math, without the drop (and some kind of vehicle like a reusable SEP vehicle) it would take almost 100 years to pay off the Launch Costs Alone! but things like he3 would help with energy costs. If we had a space elevator, we could put up solar power satalites and pump the power down the cable, but otherwise, you loose too much power beaming it down to make it worth your time. I can see people liveing in concrete domes on the lunar surface to support minning operations. with the drop andthe SEP, you could get to the moon with your belongongs for about $200,000. that would be possible! then, with the doubtlessly high wages on the moon because of the doubtless labor shortage, you could save up and bring your family afterward (just like america in the late 19th and early 20th centuries. this would just set off a chain reaction, pulling thousands of people to lunar, martian and maybe even asteroid mining colonies.