If you know someone who is a member of Costco then they sell a set of the Roughneck bars for a really good price. When I bought mine the (years back) they were same price as the big one on it's own elsewhere.
Simple to knock one up heres mine i made ages ago 600mm long 90mm between the forks,make these long enough to get under the whole board,if i need any more omffff i slip a pole over the end,comes also handy for upping floorboards to
We made one like the one shown with a bit more on the back like a rocker to give more leverage. It was at a factory where we repaired a fair few pallets and it did a good job. The pallet nails are very tenacious so if you rush they split the boards anyway. We had some pallets in once made from dark wood and I salvaged some boards from them which when sanded were just like (probably were) mahogany.
I've broken a few up since getting my woodburning stove, and I have used two methods.
1 Slice it to bits with the evolution circular saw
2 Bash it to bits with the maul
Circular saw makes more mess with dust everywhere. I have a couple of big chunks of timber that I put side by side with the planks over the gap between them, hit with maul and the piece splits easily. Corner blocks come off with the aid of a BFH. I think the maul is the best way, certainly best exercise. I have the roughneck bars from costco so will have a go with them next time as well.
Obviously if you want the wood for something other than smashing to bits and burning don't take my advice!