If you've got older 4 shop style fluorescent fixtures, you can change out the tubes in them to LED. I've bought LED tubes at Costco for less than $20/pair and they work in any old fixture. They are much brighter than the fluorescent tubes.
Really easy upgrade.
Another option is to buy fixtures with bulbs. My son in law bought about 20 new fixtures for his 25x25 shop. He got a smoking deal on them from Costco He'll probably need to wear sunglasses with them on.
