I recently bought a new tent, is it worth the extra $40 to purchase a footprint for it as well? Or are there alternatives that can be found on the trail or even made at home?
If you don't mind the extra weight, I would say definitely go for it. It helps to protect your tent, and $40 spent to protect a $300 to $400 item is well worth it in my experience. It reduces the chance of damaging the bottom of your tent on sticks and rocks. It is also useful, as Gonzo states, alone if you are setting up just the fly and the footprint for a quick break out of the sun.
I will also add a qualification to my statement that it is worth it if you are going to be camping more than just a few times a year. Like most things, the chance of damage goes up the more frequently you use it, so if you're out every weekend, you'll be able to make use of it a lot.
I've been surprised by how durable tent floors are. I've never used footprints, and I have a silnylon-floored tent (i.e. not very durable material) that has lasted hundreds of nights and still doesn't have any holes or thin spots. So really, I would call it wasted money and weight in your pack to carry a footprint.
If you forsee using the tent in "fast pack" configuration, i.e. no tent body, then consider getting the footprint just for that.
Personally, I've found it useful to have just a footprint when backpacking or camping in mild climates to reduce the carrying weight. While just a rainfly and footprint won't keep bugs out, it will protect you from rain and wind, and will be much lighter without all of the tent fabric.
With the potential for severe weather conditions, however I would bring a complete tent.