I find it better to use the Latin names of plants than the English to minimize the risk for confusion. Marigolds are several very different kinds of flowers, f ex calendula officinalis and tagetes erecta. My bunnies will eat the leaves of the tagetes erecta but won’t touch the calendula. French tagetes is not edible at all.
If you’re in the northern hemisphere it’s probably too late in the season to start growing anything now, but for next year you could perhaps also grow various types of mint, tarragon, parsley and basil (perhaps best grown indoors in pots if it’s a cold climat), leafy lettuce like oak leaf and Australian red and green, and my bunnies´ great favourite: sunchoke or Jerusalem artichoke (Helianthus tuberosus). They eat the leaves, I eat the tubers =) They grow very willingly and need very little fussing over. I’m also in a “bleh” climat. This year’s summer’s been lovely and warm and everything has grown and prospered, last summer was cold and windy and useless for growing stuff.
Bunnies can also eat f ex zucchini but mine won’t. There’s always a discrepancy between what they can and are allowed to eat and what they actually will eat.
Dandelions are a whole group of plants, Taraxacum. They’re all bunny-appropriate.
I’m in Sweden so I can’t tell you anything about prices of vaccinations elsewhere. I pay the equivalent of 46 USD or 30 Pound Sterling for the double vaccine (myxo and rvhd) once a year, per rabbit.