My birthday is coming up and coincidentally they are having a pretty good sale on LCPs at the PX ($260) or LCR .38 ($375).
Primary use is a small concealed carry pistol. I currently carry a M&P compact .45 and am looking for something to fit the "this is what you carry when you can't carry anyhing else."
Which should I get or should I hold out for the LC9 or LCR 357?

ETA: I have some 9mm in stock and am not opposed to buying 38/357 (as I already have the reloading setup), but is .380 still scarce/expensive?

If small is important, consider the LCP.  I have had no problem finding 380 ammo.

At the moment, the LCP is the champ of really small pistols in a caliber that is at least somewhat useful.  The LCP will fit in a pants pocket without printing if you wear your jeans short of skintight, tho' a pocket holster (and nothing else in the pocket) are necessary for safety.

Don't own an LCR but I do have a Centennial, which is about the same size and a lot harder to hide in a pocket or other minimal garment.  If you really want an 'all the time', the LCP is the deal.

I've seen a few complaints about them, but every one I've seen personally worked all the time.  Counting all the guys at our Club, that is someplace north of a dozen, and a lot of that shooting is with reloads.  My personal LCP is past 700 rounds and has never missed a beat.

Three eighty ammo shouldn't be too hard to come by, but it's not the bargain that 9mm often is.  Think about Gold Dots for social purposes, and FMJs for everything else...but stick with brass cased ammo.
Moon

The LCP is a nice little pistol and pretty accurate  for what it is. Ammo. prices are not as good compared to 9mm, but the pistol is meant to be shot little and carried often, but I would still take it out to the range every other month or so. Recoil is not bad and the gun does not ride in my hand as does the Kel Tec. The LCR takes a little getting used  but is a nice firearm. I ccw the LCP in a iwb holster and it is very comfortable and reliable. Ruger has come a long way with their newer firearms.

I recently sold off a Glock 27 and picked up a LCR .357 for CC purpose.  I could not be more pleased.  The LCR is outstanding and fairly nice to shoot with .38 loads.  .357 loads are manageable, but not much fun.  Having said that....I will probably still carry it with .357.  I figure that, in a situation, I won't much care that the .357's aren't much fun to shoot.  YMMV.  I work with guys who went with the LCP.  They advised that they qualified with it, but other than that it is not pleasant to shoot.  SO.....my vote would be the LCR.

Having had them I would definitely go with the LCP.  Ammo is plentiful around here.

If you choose to go with the LCP I recommend painting the front sight with white nail polish for better visibility.  I had to do several of them prior to firearms qualification at the office.  You will see what I mean.

LCP for best concealability, ammo easy to find at, good prices.

I completely agree with this. I have both the LCR and LCP. The LCP is my everyday pocket pistol. The LCR is my secondary pocket carry.  

LC9.  If you're going to carry a gun then carry a gun, and the LC9 is thinner than the LCR so it conceals easier.

LCp

Thanks to all for the input.
Even though it was an ordeal at the gun counter (in at 0800 out at 1200), I ended up with the LCP and couldn't be happier. Now to get it to the range for a proper break in/familiarization.

Go big or go small.

IWB a double stack or go for an LCP in the pocket.
The middle ground of the two isn't a smart move IMO.