http://raptornails.com  Check out this web site.  They sell plastic staples. You can sand them flush and they disappear under your finish. 

the T50 is a very popular staple type used for strip built boat building with a variety of manual and power stapler options that handle this staple.

the crown (width) of this staple is 10mm or 3/8 inch which fits nicely within most strips. (most strip boat projects recomment strips that are 1/2 to 3/4 inch wide)  much wider than this and you will bust up the strip by punching the hole too close to the edge of the strip.

you should use the longest staple available which is 14 mm (9/16).

that should get you through most simple projects that DO NOT have serious wood bending/holding power requirements.  i say this becuase my experience is that the holding power of the staple leaves a bit to be desired where you are applying a lot of force to bend the strip. (note, strips are often spec'd to 3/16 to 1/4 inch.  so that only leave about aquater inch of the staple into the underlying form.  which is typically not a problem except when there is a lot of bend being applied)

if i was doing it all over again, i might search out a staple type and associated stapler that had approximately the same crow that is 3/4 inch in length.  this would also allow you to set your staple to leave a good 1 mm of the crown proud of what you are stapling to make it easier to remove the staple when done.

again, the T50 is very popular with the strip built community and is a very popular/inexpensive and easy to find staple and stapler type.....so should be just fine for most standard projects.

Pneumatic staples could be very difficult to remove later on.  I use them for work, and the really hold.  You would need to lay a scrap over the good strip, and staple through both layers, then break the sacrificial piece away to get a grip on the crown of the staple to remove it.  I use narrow crown  when building cabinets, mostly for backs, and odd hidden pieces that need to be attached.  

 to build on dave's point above, when stapling for a strip built (manual or pneumatic), you want the crown of the staple slightly proud of the wood so it can be removed.

you will want a number of practice shots to sort out the staple gun, particular staple used, the wood you are tacking down and the underlying material/forms you are stapling into.

any pneumatic stapler you get should have an adjustment so you can change the stapling force.  and you will need to adjust that so not to blow through your strips.

   Thanks everyone for the advice. Think I'll stick with the more traditional staple gun.