"I can't afford to buy a bunch of lavender, anyways, so it would be a slow process."
If cost is a limiting factor please note that you can propagate lavender from existing plants. Once you get some lavender plants established and growing well you can take cuttings and grow new plants, saving yourself the expense of buying them from a nursery.
Here's a link that describes the process:
https://www.thespruce.com/how-...
I'd also reinforce the above advice to try different varieties to find the varieties that work well in your yard. And I'd suggest you think about trying different sizes of lavender to give your yard some variety. Color also varies somewhat between varieties so you can consider that as well.
Good luck and please post pictures of your progress
