$500 should get you a larger mini-ex rental for a couple days. Getting a mid-size machine is a lot harder, around here anyway.
"You must be the change you want to see in the world." "First they ignore you, then they laugh at you, then they fight you, then you win." --Mahatma Gandhi
"Preach the Gospel always, and if necessary, use words." --Francis of Assisi.
"Family farms work when the whole family works the farm." -- Adam Klaus
Renting a mini backhoe/excavator is something you could do yourself. Easy to operate. You can get a lot of work done in the matter of a couple hours. If I were putting in something as easy as swales, that's the way I would go simply because of the timeliness. Time is my most valuable and scarce resource on my homestead. Over the past ten years I've been forced to use it more wisely. When I first started, I did everything the slow way, by hand. I was rather hardheaded, so it took me a while to realize that my greatest detriment wasn't lack of money, but lack of time. But since I don't have lots of money either, I have to balance time against expenditure. But in this case, I'd be sorely tempted to rent the equipment. Do the swales, dig some pits for future hugel beds, scoop out a few pond/water catchment holes, scrape together a few piles of dirt for future use.
It's never too late to start! I retired to homestead on the slopes of Mauna Loa, an active volcano. I relate snippets of my endeavor on my blog : www.kaufarmer.blogspot.com