If you have a Walmart nearby they carry Novolin R for ~$24/10ml. It's still expensive, but better than the $120 or more for Humulin I was spending at Costco (and still better that the $300 charged at some places).
Through work currently we can use a web site to help find your cheapest place for prescriptions. One bottle of Novolin R like you said about is about $25 from Walmart for cash price. One bottle of the same prescription with a discount coupon is $138 dollars.
That's still cheaper than Novolog/Humalog, but how in the world is it more expensive to buy insulin with a prescription and insurance than without? When I pay a 20% co-pay am I essentially paying my insurance company the extra money?
Of course it makes no sense that the fiddly details of how you buy medicine matter to the tune of 5x. I guess part of the problem is that an awful lot of people are insulated from the costs of their medical care.