Personally I'd ignore the model and look at the product.
The important thing for most users (and because they're asking for recommendations I assume these aren't people with a strong opinon) is that it works for them and does so simply and reliably.
Based on this if there is a genuinely good Open Source option which has been polished in the way the typical novice user would want it to be (Firefox would be a good example) then that's the starting point but not because it's Open Source, but because it's a good product AND the price is good.
After that I'd tend to offer them the choice between something which might require a little more support/effort/tolerance but might be free and the pay alternative and let them decide - but do so honestly and openly, explaining not just that one was free but also potentially any limitations (so Open Office Calc while pretty good is not to the same standard as Excel 2007 and if they are a serious user you should let them know).