I spend quite a bit more than that per month, both for my own sites as well as client sites. Here is what I spend it on:
1- Developing portals. I have 200+ portals spread across 60+ class C IPs. I develop content with links to my clients sites and to authorities. Then I build Social bookmarking, web 2.0s and other such 'free links' to the pages I develop. To top it off, I shoot xrummer and scrapebox links to the web 2.0s, SB, etc. This way I ensure 3 levels of link laundering.
2- I buy 100s of links off fiverr and other such sties. But it takes time and experience to make this worth your time.
3- I have VAs create manual links wherever my competitors have links. I use tools to find the places my competitors have links, then make my VAs get links there.
4- I hire Copywriters, pay for video production, buy cheap scripts in mass to produce content for web 2.0s, review sites, video sites, doc download sites, etc. There are 100s of places on the web where you can get quality free links if you have content, videos, small scripts, etc. And if you are smart, you can make them appear 'relevant' in big G's eyes.
5- I have a very large list of people I know over the years who have their own private network of sites. For a fee or a favor, I can generally get access to them. I know over a dozen different people with thousands of sites in total over thousands of class C Ips.
6- I set up sites that I use to give links out and get links in exchange. Scrape whois info to spam people for link exchanges. Although I'm cutting back on this as it is less useful now a days.
7- I buy up existing sites that expire.
8- I sometimes build 4th level links to the 3rd level links... I'm doing this more now.
9- Press releases
10- Link bait campaigns
11- Anti-linking campaigns (I make sure links are taken down from where my competitors got links)
12- Secret sauce and other techniques
I rank for some of the most competitive single keywords out there using this. Having said that, these techniques mean little unless you do it well, cover footprints, and stay smart. One slip up can mean your site gets a manual review which it might not pass.
Oh, I will also say I pass all the major updates without a hitch using the above mentioned methods. Panda, what panda? (I did get slightly hit on one of my clients sites by Panda, but it is back)