There are good (free) compilers/environments for PICs to be sure, but since there are so many of them (both pay and free) there isn't as much development standardization. I'm often amazed not just that Atmel gives away a great assembly compiler/programmer/simulator environment, but also in how well they cooperate with the WinAVR guys, both in integrating the WinAVR GCC compiler into AVRStudio, and in little things like providing both assembly and C example code in every datasheet. I'm biased to be sure, but I used PICs before I got started with AVRs, and for that and other reasons I'm glad I switched.
You might want to look instead at a slightly different version of that board from SparkFun, the 20 Pin AVR Development Terminal. It's almost the same board, for the same price, but wired for a 20 pin AVR instead. It has a 10 pin programming header, which isn't standard any more, but you could make an adapter for the more modern 6 pin programmers (it's the same pins with extra grounds and an optional activity LED line). Also, you could probably adapt the Orangutan-Lib LCD code to drive this one by changing the pin definitions to match its wiring.
It doesn't come with a CPU (nor does the PIC version, although they are both pictured with chips, NAUGHTY!), and some of the recommended ones are oldies, but it's pin-compatible with the ATTiny2313. ATTiny's are what they sound like, ATMega cores with less memory and fewer hardware peripherals (for less money), and the 2313 is the ATTiny model with serial hardware. You can get it from SparkFun here for $2.88, which is a little more than elsewhere, but you might as well save on the shipping. The 2313's are fantastic for little single-purpose sensor/controllers on a serial bus, and should be enough to format serial data and display it on an LCD (not much more though). I used one here to sample a photo-gate tachometer, drive a 7 segment LCD display with the RPM speed, and send the data back to a laptop for logging, which used about half the flash memory.
If you want this board though you better decide quickly though, there's only one in stock!
P.S. If you just want to display numbers the kit I made that 4 digit 7 segment LCD board from retails for $20. It's meant for an older 20 pin AVR, but with a few minor kludges you can free up the serial pins on a ATTiny2313, and permanently turn on one of the decimal points or hook it to a free pin to make it software selectable. You would also need to build your level shifter circuit, and wire up a programming header (or program the chip off-board in a socket, or my personal favorite, the clip-on programmer!).