I'm responding before reading all the other suggestions, so forgive me if they're repeats!
First, THANK YOU for asking this question! And your list of things that you do that don't cost money are fantastic -- with all of those in place, well, I can't speak for all femmes but I know that for myself there wouldn't have to be a penny spent and I'd have a delightful time.
Overall I'm WAY more impressed by someone who is honest about living within his/her means and who is making the effort to find creative and enjoyable things to do than someone who backs off and does nothing because she can't currently afford the type of date she's like to go on, or someone who gets themselves into debt to "impress" me.
Just don't make a big deal about it being a low-cost date - don't act embarrassed, don't keep apologizing, in fact there's really no reason at all to say to her that you're trying to keep the costs down, because that just puts your date in an awkward position.
I will tell you that one of the very best dates I've ever been on in my life started with a simple picnic lunch while sitting on standard beach chairs at the beach -- with foods direct from the grocery store or scavenged from her kitchen, packed in a basic canvas bag, and an inexpensive bottle of wine -- followed by ice cream at the boardwalk and a walk around town. It was the best date because at every moment I was made to feel pampered and special (all those "don't cost anything" things in place), but at the same time I was fully respected for my intelligence (lots of different conversational topics as we ate and sipped wine), I was allowed to be surprised by it (I like to not have to OK every plan), I didn't feel pressured for anything, it was light and romantic and fun instead of more formal and constrained, and I enjoyed every single moment of it.
And while not every date needs to be (or should be) a surprise, still don't be going to her and asking her to ok every part of the agenda - if you don't know her well yet, maybe check in and verify that she likes doing that sort of thing (some folks just don't like art museums or sporting events, for example) but work out the details on your own - she'll appreciate you for it!
Some no/low cost ideas that I personally would very much enjoy include museums, free outdoor plays/concerts in the summer, bike riding or walking through a park or along the beach, festivals/parades (ethnic, holiday, small town, etc.), a small-town or college ball game, fireworks, or even just getting together with a couple of friends who you know to be compatible and easy-going to do a bbq or play cards.
I know that in some cities, they have a weekly email that goes out that lists all kinds of plays, concerts and other events for that upcoming weekend for which you can get typically half-priced tickets. Maybe see if there's something like that around you?
Don't be afraid to plan a deliberately casual date with a Femme -- I'm guessing that most of us enjoy those jeans/shorts and t-shirts kind of dates just as much as the dress-up ones! But especially if she doesn't know going into it exactly what you'll be doing, please be sure to give her a general idea of what to wear. For that date on the beach, my date told me in advance that shorts or a simple sundress and sandals would be best, and I really appreciated that.
With an attitude like yours, you're going to make some Femme very happy to be dating you.
