I had a choice three years back when I decided to get back to cycling after about a 40 year break. I went with a basic 20+ lb bike as I wasn't sure how much I was going to use it. After putting about 42,000 km on the bike, I've decided to upgrade in a big way. I would push through and see how much you take to it. Too many reach for a more expensive bike at the outset and then end up putting it on Craigslist at a huge loss. If after six months or so you find you're riding a fair bit, reward yourself with an upgrade.