All good points. I have noticed when people ask these questions what might help is to point them to cheap upgrades. Some of these do violate the " no-change " rule, but are not in anyway noticeable. The best of these is bedding the receiver. For the cost of a container of JB Weld and car polish you can make a more accurate firearm.
http://www.theboxotruth.com/docs/edu75.htm