This is an interesting post because of the restrictive parameters.
If you are limiting yourself to Wal-Mart rounds, then I guess you are just stuck with a .243, because Wal-Marts stock darned few calibers these days.
Three very popular rounds that immediately jump to mind (but not Walmart rounds) are:
7.62x39mm
6.8 SPC
6.5 Swede
All three are light recoil and would really shine at 150 yards. All three can be bought at really reasonable prices from the big catalogue companies, like Cabellas.
The .357 Mag, in regular factory loads are really limited to about 110 yards if you are talking about anything bigger than a Woodchuck.
A last thought is the .30-30 Winchester, using the Managed Recoil Ammo by Remington. Folks I've talked to seem to love this. If you go on-line, it says that Wal-Mart carries this. But in two Super Walmarts I have been visted, they don't have this ammo in any caliber.
Hope this helps.
Mannyrock
Some short answers: The .30-30, using the managed recoil ammo by Remington, fits the parameters perfectly. Who cares what the trajectory is out to 150 yards? It is irrelevant for hogs or larger. Problem: cost about $20 per box.
The .357 mag, using the custom high power ammo by Buffalor Bore (or is it Garrett?). Gets you pretty close to a standard .30-30 round. If you just use regular factory ammo, I have to agree that about 110 yards is the max, and that can be a little iffy.
Has anybody thought about the 6.5 Swede, using factory ammo? A very light recoiling and very effective round.