Allan's suggestion would be my choice, but the other option would be to have a separate Price Table, which would have a Price Field as well as a DateField which would document when that Price became effective. You'd have to check a Date Field on your Record and compare it to the DateField in the Price Table, each time you needed to reference the item's Price.
As I've stated, I'd go the route of storing the current Price in the original Record.
Linq ;0)>
The problem with making anything foolproof...is that fools are so darn ingenious!
All posts/responses based on Access 2003/2007