What is the best plant fertilizer but with a sensible price?

Well for potted plants you might want to get some worms from the yard and put them in the pots with a few dead leaves mixed into the soil to distract them from the roots. <- That helps a little with fertilization and aeration but it's not really the best. Well if you didn't know, there are almost always 3 numbers on a package of fertilizer, and those numbers stand for the ratio of ingredients that the fertilizer has. For general use fertilizer I would recommend that you use a fertilizer with the same 3 numbers that's 15 or higher, like a 17-17-17 or a 20-20-20, that helps with all aspects of the plant. Just go to any store and look for the cheapest kind like that or buy in bulk.

If your county has a recycling center they may make and sell compost as cheaply as they do here. ( Frederick county Maryland; $8.50 a cubic yard) I use that as a feeding mulch as well as my own compost. One can soak 1 part compost to 4 parts water in a five gallon bucket to make "compost tea" and that is an excellent fertilizer when used as irrigation.

depends on the size of your operation but if its not full size garden size and just general couple of beds few potted plants osmocote is easy to use, goes a long way, wont burn things, and is effective .. also to get some more immediate results, Bonnie herb and vegetable liquid mix is quite good ...

You can try adding vegetable waste manure for good growth. Refer: http://scienceray.com/biology/medicinal-plants-like-vegetarian-waste/

Poop....

your own poo