Thanks to Diane from In My Own Style, I now knew to buy vinyl decal material in the colors I wanted (in this case, black and ivory to match the walls,) a bunch of spare X-acto knife blades, and some clear acrylic spray adhesive in order to get started. I bought the decal material from craftvinyl.com (5 12x24 sheets of both glossy black and ivory,) and the rest of the supplies from A.C. Moore. Additionally, I also had a jar of clear, water-based varnish on hand, as well as foam paintbrushes for extra waterproofing power, which will come into play later.
Please note that Diane's DIY vinyl floor transformation took her two hours to complete, and she was only changing the accent colors on her floor. My own project took about 36 hours of effort in total, since I had to cover every single tile in my little bathroom. In other words, make sure that you have some extra time if you plan on performing this project yourself! There were three different sizes of tile to account for, and so I had to measure and cut the vinyl accordingly. I placed the vinyl on the tiles according to Diane's instructions, and made sure to spray everything with the clear adhesive when I was done. However, I wanted to make sure that all that effort was indeed going to last, so I added the clear varnish on top of the adhesive once the latter had dried.
Once I was done, the effect was lovely, and everything seems to be holding up particularly well! If and when I move out of my apartment, a bit of turpentine will get rid of the vinyl decal/adhesive/varnish combo, and return the floor to its original Mamie pink if the landlord so desires. (Can't imagine that they're that married to the color, but y'know, it's their call.) Total cost? Slightly under $30 -- including shipping -- for the vinyl, (Check CraftVinyl's Facebook page for coupon codes!) with an extra $12 spent on both the X-acto blades and spray adhesive. I had the varnish and brushes on hand, but the varnish cost about $5 when I bought it, and the brushes are $1 for a large package at any Dollar Tree you can find. So when all was said and done, I redid my whole bathroom floor in a rental-friendly way for less than $50. Check out the results below! (Apologies for the crappy camera phone quality.)