Please have a look at Explosive Projectiles, it has the last sales all at +0
which they weren't

Thanks

Ah it is because they are unit price TT+
Would it be better if they were %?

Honestly explosive projectiles are going to be TT food in the very near future. Everything drops them and quite often at that.

As you cannot buy them from the TT there might be a small markup if you have decent quantities. (e.g. 100K)
Currently auctions at 101% do not even get bids so for me it is TT food already (actually still storing them as long as I do not need the peds).
Things might improve marginally if there are low level launchers available at a reasonable price, but only marginally

Once launchers become commonplace I think that the main source will be large quantities of projectiles found by the users with the secondary source being trades for only like 101-102%. They will never be extremely rare, and there won't ever be a massive shortage of them.

There are a few issues with PEAuction due to the changes they have made in how they release the auction information. I will relay everyone's concerns about PEA to Travis as soon as he returns. He cares a lot about our two sites and so I am sure they will be rectified rather quickly.