It's not a bad price, but it's not a steal either. Those are almost certainly amorphous silicon panels. That type of panel (as opposed to monocrystaline, or polycrystaline panels with individual cells) has the shortest lifespan, and also take a big drop in performance in their first year of exposure to the sun. Crystaline panels are often guaranteed to produce 90% of original output when they are 25 years old.
You'll also never get 45 watts out of it except under carefully controlled laboratory conditions (true for all panels, they're rated under best possible conditions which you'll never see...) but Harbor Freight seems even extra generous with their ratings. I have one bolted to my roof right now, their so called five watt panel. I've never seen more than 3.2 watts, and that was under very good conditions (absolutely clear sky, solar noon on a very cold winter day, with snow in front of the panel likely having a reflecting/concentrating effect). Typical output was less than 2 watts. Obviously not the same panel, but perhaps representative of what you could expect.
Best regards,
troy