Ive seen permaculture courses that go for (online) $500 with a sliding scale if you cant even afford that... all the way up to thousands (i think the full permie course 10 weeks at zaytuna is about $6K)
but there are affordable options if u want to do it there is even one australian based online course that lets you pay in installments of 200ish x 3 just pay as you go.
if you can get away for 12 weeks there is a free PDC course at sadhana forest at both their Indian and Haiti communities. www.sadhanaforest.org
I think you should do it because as someone else pointed out it is much more than just gardening