A few months ago I was in the situation of needing an assistant. I couldn't be arsed training one, so had either the option of automating more or working longer hours. I chose to automate more.
Now I have 2 VPS's running auto tools 24/7. One is from a respected supplier, loaded with my licenced tools. The other is a BH one with cracked tools on it. (mainly because of senx - I ain't paying 2 x $167 a month for anything. I'll happily pay it once, but not twice). I had to upgrade my video card to allow 3 monitors, so now run a VPS on the 2 outside monitors and work on the middle one. (3 monitors is not essential - I just like seeing them tick away all day. I would advise 2 though if you're going to run a VPS, most video cards will handle 2 monitors).
Since changing to this setup my workload has increased immensly, and more importantly my rankings have also. As for costs. I pay about $44 for the respected VPS and $50 for the SEO one per month. The video card cost me about $200 and the 3rd monitor was $99. So say $300-$350 for setup and $94 a month for VPS. So for a 2 year cost (including setup) it's about $2600. Which with the electricity savings would have to be pretty on par with buying 2 more puters for home (with the associated repair costs you'll almost definately incur).
I'm not sure where you are, or how your ISP's charge. But here in Oz we still pay for bandwidth so that makes the argument even better for VPS's, as it would cost me hundreds of $$$ per month to use the kind of bandwidth at home that I chew thru with 2 x VPS's. Another factor would be the speed. I tested a SB run with all the same settings and a list of over 250K and the VPS completed the task in about 1/3rd of the time as taken with my home connection.
Hope that helps