We replaced both with the cheapest available laminate option from Home Depot.
We used a jig saw (which is probably not the right saw) to cut the holes for the kitchen and bathroom sinks.
We were able to use the scrap piece from the short side of the kitchen corner as the top for the bathroom. Because kitchen countertops are deeper than bathroom vanities (fun fact!) we cut a few inches off the back so it would fit on our existing vanity. Laminate countertops aren't exactly luxurious, but the are a perfectly acceptable option for a range of projects. Due to digital photography, the laminate images are better than ever, with less repetition. They are easy to cut and install, too.
Edges can be a bit tricky. Exposed edges must be finished by gluing on a strip of laminate, then filing it until flush with the countertop. You have to be careful not to damage the countertop as you file down the edge. It's not to difficult, but it took me a couple tries to feel competent. Luckily, the vanity top in the master bathroom sits between two walls.
Assembling corners isn't exactly a walk in the park. You have to buy a joining kit, which comes with special glue and hardware that tightens to pull the two pieces together. The actual assembly isn't as difficult as trying to find a decent place to do the work. I cobbled together an appropriate workstation using sawhorses and random bits of wood.
If you need to cut down the countertops to the correct size, a table saw is the best choice. ...I take that back. The best choice is getting the countertops cut professionally. Depending on how much you are ordering, it is completely worth the extra money for laser straight, perfectly measured cuts.
