Um, I just bought a little bitcoin at a time until I had a whole BTC, but that was back when it was about $250 per Bitcoin.
You can do that of course, the fact is that it can also be simply done by doing signature campaigns, its an easy method and its profitable and almost has zero risks.
If you really want to make the most out of signature campaign then you need to develop the membership level and trust score of your account to a high because people like newbie and members make little to nothing through signature campaign, hence you need to make your account is okay for that before you can talk of earning decent amount of money.
Yeah, me I am a Sr. Member and I do not mind my income in signature campaign as 0.006 BTC max earning in a daily basis is not so big for me, sometimes I just save it for a week and then I use the money in gambling, at least I am not talking a big risk. My real goal really is to make 1 BTC through trading.