This is very unprofitable at the moment.
It's only for hobbyists.
I took a look at this user's statistics:
http://ptsweb.beeeeer.org/user/Pbv7ufWTykwhgKrXZTnLAd2FCMX2bNCb9oI calculated that 0.12703 over 4 days using (2 cores) is the equivalent of 0.4763625 protoshares a month using 1 core.
0.12703/4/2*30 = 0.4763625 .
Now the price is around $11 a protoshare at the moment. This means $5.2399875 mined, for the cost of $5.
Caveats!
The difficulty has jumped sharply. The statistics are from 1 month ago, now it's much more difficult. You won't even breakeven. From what
I've read the amount of protoshares a day has more than halved so miners are paying $5 to make $2.50. Furthermore, if you decide to drop out at any time like the one above, you won't even be able to cashout...
In this situation, you have effectively made nothing...
I also looked at the cloudatcost, but it appears it is aimed more at people that are using unlimited bandwidth and running a youtube views bot rather than something that places burden on the CPU.