If you've been using a good synthetic oil, then there is likely little or no gunk/sludge in the engine.

If you've been running non-synthetic, even with regular oil changes, there are good odds that you have some buildup. Not too hard to do it yourself, saving about $100-- before draining oil at next change interval (about 3,000 miles), add a can of AMSOIL or BG engine flush. Then fast idle for about 15 minutes before draining oil (Read instructions on the can). Neither of these will hurt anything, and could be helpful. The cleaning done at the shop might be more thorough, but also will set you back a lot more than the $5 or so.