Poplar is one of the less expensive hardwoods. It’s also fairly soft, considering it is a hardwood, which makes it easy to work with. Poplar is very light in color (almost “white”) with some green or brown streaks in the heartwood (the wood that comes from the center of the tree). Because poplar is not the most beautifully grained wood, it’s almost always painted as it does take to paint very nicely for a uniform finish. Poplar makes for great table bases (often painted, with a stained tabletop of a different wood), drawers, cabinets, hutches and more. Poplar is a very common wood that is versatile and cost efficient.
I, too, would pass on the Jawhorse, and agree with the suggestion of a solid bench. (Remember, it can double as a desk if space is limited.) A used solid-core door can be a starting point, but there are better options, such as laminating your own from scrounged 2x4s. Spending time at flea markets looking for old tools that can be reconditioned is a good suggestion, too.
Just like a hammer and tape measure, a drill is something a lot of people already keep on hand for small household projects. Danny and I started out on a SUPER cheap drill when we first got married and quickly learned that this was not something to cheap out on. If you plan to do much woodworking, invest in a quality drill. It doesn’t have to be the best of the best, but do at least get a mid-grade drill.
Finally, at the beginning you'll do just fine with a basic set of router bits that run ~$40. A starter set will typically include straight bits for edge matching material, a selection of edge finishing bits, and some joinery bits. As you work on a few projects you may find that more specialized bits are needed. But specialized bits are expensive - so purchasing them as you have a specific need makes more sense than buying in anticipation of a need.
The best advise I can give you is to get and read the book "Hand Tool Essentials" by the staff of Popular Woodworking before buying any tools. It is sort of an inexpensive crash course in hand tools. Chris Schwarz's book "The Anachrist's Toolchest" is another good source of information on handtools that I found to be a fun read. Use the internet to learn all you can about a tool before buying. The tools you need are dictated by what you want to build.
The next important hand tool for the woodworker is an accurate tape measure. Get a retractable one that is at least 25 feet long. Any longer than that, and you start having problems getting it to roll back up. Since measurements on large scale projects can be very susceptible to even the most minute measurement variations, you’ll want to make sure the “hook” or tab at the end of the is firmly attached, with no give. When they get loose, you’ll have as much as 1/8” variation in your measurements. This can add up to some severe accuracy problems in the long run.