I was in the same dilemma as you, since I wanted to start acquiring SPS and my Amazon Nicrew light wouldn’t cut it. I was originally going to get the a160WE tuna blue, but I searched my local craigslist and found an AP700 for a pretty good deal. I know it’s overkill for a 20L, but I’ll have a light that I won’t have to upgrade for when I upgrade my tank.
Try searching craigslist, you just may find a good deal.