If you are willing to pay $2,500 for 100,000 miles there are plenty of ways to do that, while flying and taking vacations. If you want a cheap 100,000 miles it is fairly easy to get that many miles for $1,000 by flying.

With the triple miles bonuses going on right now you can fly MIA-SIN and earn 92,000 with UA (if you are elite) or 69,000 (non-elite) on a $700 ticket. That leaves you $1,800 to spend on hotels, clothes, spas and massages, and then you still have those miles when you get home after a few days of luxury.

Now if all you have is money and no time, then you can just buy miles and hope you can squeeze out enough time in the work schedule to use them.