....  Also, I'm not sure what percentage of Apple apps are free.  I would assume there's a fee associated with most of them.
Thanks for any advice on this.
Richard
		
		
	 
As you noted, mileage will vary with owner.  You did peek my curiousity so I added up the present cost of all the apps currently on my ITouch.  (I have had it about three years.)  The total was $60.00. Most of the cost was in reference and utilities.
To help you judge your own costs (and how you can cut into my $60), in a reveal all mode, here are the apps currently on my ITouch.
Games: Angry Birds and IChess Pro.  $1 each or $2 total.
Reference:  National Geographic Field Guide $10 and Chirp! (bird songs which are also on the former field guide) $3.  (Yup, I'm a birder.) National Geographic Atlas. $2.
Ebooks:  Currently there are three ereaders on my ITouch (with two others removed).  Zero cost.  (But then there are the books.)  Plus a B&N and an Amazon app which allow you to browse their stores, etc. Zero cost.
News and Weather:  NY Times and Local newspaper plus a free version of the Weather Channel.  No cost.  (You can also use the Safari browser to access newspapers, but many newspapers have specialized apps - some of which are better than using the browser.)
Utilities:  Convert (converts all sorts of measurements plus currency) $5. Docs to Go (allows you to carry and make changes to spreadsheets and Word documents plus opens the same two kinds of documents plus .pdf documents attached to emails) $10. TravelTracker. (Trip organizer) $3.  Gas Cubby (tracks gas costs, mileage, and auto maintenence) $5. Secret! (Password keeper plus anything else you don't want to be seen if you misplace your IPhone - syncs with computer version) $7.  Informant (calendar and task recorder) $13.  (Note:  The IPhone will come with a calendar which for most people works fine.  I have meetings on - like the first and second Mondays of the month.  The free calendar cannot handle that.  It will only let you do monthly meetings on a given date.)
In general, most apps are free or have a trial version.  Never buy without tryijng.  Also, with a rare exception, all apps allow you to do updates for free when they come up with newer versions.  
Hope this gives you at least a start as to what you might expect.