I'm going to be a bit of a voice of dissent, here. Having sold off a couple OM .45s in the last year, I can say that the values quoted can be difficult to actually get. Ruger prices have softened since the economy tanked. I really like OM .45s - they are one of my favorite Ruger models. However, they are not as universally appreciated as some other models, so they can be slow sellers at times if one is seeking the "market" price.
Not that long ago, I tried to sell one in similar condition to yours here on this forum for $650 shipped. Didn't get a single bite. After months of trying to sell it, I finally traded it for what I considered to be $500 to $550 trade value.
Anywho - I'm not arguing the values given. OM .45s should be worth more than Flat Tops, in my opinion. However, if you decide to sell it, you may find you have to wait a while to get the quoted numbers.
BTW, it appears your stocks have stainless hardware, which would make them incorrect for this gun. That will ding the value a little bit if a purist buys the gun.