NOT spending money on a hardware load balancer when you have the requirement to do so will hurt you considerably in the long run, however most folks don't know one from the other, and why one man's load balancer is another man's small fortune.
Now it's easy to find a hardware load balancer that has been tested by both the manufacturer AND Microsoft specifically to support exchange 2010. I was happy to see some low cost alternatives to the more expensive load balancers on the market, having worked with both, each has it's place, however doesn't always make budgetary sense.
This page lists 8 hardware and 4 software manufactures at the time of writing, including favourites such as kemp, barracuda, f5 and more. Most of them list the deployment guide on the same page, and after having had some recent pain, I can assure you that simpler and cheaper can often save you over that rare feature required for a corner case deployment. I can confidently saw that with the number of manufacturers listed, that one or more of them will have representation, no matter where you may live, at a fairly decent cost too.
Before you think that this lists only hardware load balancers scroll down, Kemp, F5, Citrix and a10 all offer software equivalents of their load balancing solution, some of which run both on Hyper-V, vmware and others.
Load balancers do a fantastic job, and in any decent size deployment they earn their keep really quickly, however make sure that you buy the load balancer suited to the task, load and the environment. Software may cut it, and hardware may be required and either will beat windows NLB at actual load balancing based on application state and application load, but load balancers don't have to cost a fortune anymore. A number of folks were disheartened at the cost of early load balancers, however I think you'll find that the entry level had dropped dramatically to the point where your two node cas array could do with some load balancing love.