Shackle flip is cheap if you have the tools, but it isn't free because you still have to buy the hardware to reattach the hangers. Problem with shackle flip for OP is that it is only going to get you about 2" in the rear suspension.
To get 4" on a budget, the cheapest answer if you have the tools (grinder, welder, and angle finder) is to remove the spring perches, relocate the axle over the spring, weld the perches back on. Instead of doing all of that, your best budget option will probably be a set of axle flip brackets from Amazon or eBay. That will get 4-5" drop, then install a longer shackle to raise it back up some if needed.
Front, 2" drop springs. You can try cutting stock springs, but usually results in pro ride quality. If you want to try cutting, only do about a quarter coil at a time and drive between to let it settle, don't try to cut more than 2".
A 2/4 drop can probably be aligned with stock control arms, but you will likely need camber adjusters in the front. You'll definitely want an alignment after, so it'd go ahead and install them while changing the springs.
You may need/want shorter shocks as well. That should be in range of stock shocks, but still be more likely to bottom out and cause a harsh ride.
I know you are looking for budget, but DJM probably had a drop kit for this. Will have everything you need (except the adjusters) and be better quality parts than you are likely to piece together from Amazon or eBay. Might be a little more expensive, but might also be worth it.