It only costs an extra £60 for the High Resolution screen option, so you're not gonna be saving very much anyway. The only thing is that if you go for the standard resolution model you may spend the rest of your time wondering whether you should've gone with the higher res! 😀
As other people have said, generally there's no problem reading text and especially not menu bars which look just the right size. It's only certain websites that I have problems with where they've used a really small text size. But this can be fixed by temporarily increasing the text size by using the Command-'+' shortcut or permanently changing the Safari preferences option, "Never use font sizes smaller than".
Personally I wouldn't have bought the 17" model if it didn't have the High Resolution option - it basically feels like you've got a portable desktop where you can do all your work wherever you are!