went to Menards (the ONLY home improvement store within 100 miles) and picked up this:
Whole-house filter kit ($30), 5 micron filter ($2 -- good for 6 months/30k gallons), 10 ft copper pipe ($10), various fittings and shutoff valves to do the plumbing (approx $25)
So for roughly $75, this will work awesome. Not much will get through with this 5 micron filter.
What it used to look like in the corner (main water line from city coming up through the floor on the right side of pic, continuing to house off the left side of pic. "T" goes to outside spigot.
Here it is installed. Green arrows show the flow of water. After the fact I decided it would probably be nice to be able use the spigot without filtered water for stuff like watering the grass, so i'll put in a bypass pipe w/ a shutoff valve as well as a shutoff valve going to the filter so i can choose which one i use (indicated with red lines)