Get a flavoring to go with your DIY. If you don't care much, maybe just keep it simple. Grape. Or Vanilla.
Cherry, strawberry, tobacco, RYX, blah, blah, blah are more "complex" or harder to produce flavors and may or may not be to your liking. Just get a small bottle and maybe an empty bottle to mix in (so you can try a small batch). Then.... you can flavor it.
You'll want PG and/or VG to cut it with. The savings are in buying the higher nic (only as high as 48 mg for me...that's fine. Then I cut it in 1/2 to get 24.)
I think I vape at less than $ .20 (twenty cents) per ml. Depends on the sales. But it's always flavored with something. Tried to vape unflavored....yuck!