I don't think a MacGregor 26 has 1/4" stays. Probably 5/32" or 3/16" typical to a boat that size. That being said, the cheapest furling systems you'll find for a boat that size start around $600 plus shipping.
I have a Schaefer CF-700 Snapfurl system on my Catalina 27. The smaller CF-500 was too short to fit. Defender Industries has the CF-500 for $569. The larger CF-700 is $999 (but I've seen it on sale from them occasionally for $798). A good option for a cheap disposable furler. You can look at the CDI systems as well. Slightly cheaper but don't use ball bearings in the drum. Upgrading to the ball bearings puts you within distance of the Schaefer setup which comes standard with it and is aluminum versus plastic.
Honestly, a furler for a 26 footer like your will run you between $600 and $1100 depending on brand, dimensions, install options, etc. If you want to keep costs down, look at systems you can install yourself. While I prefer Harken, I'm happy with the Schaefer system I have and it is better than the CDI systems typically found on boats this size. The ProFurl B looks like a good option for your boat as well at $750.
I'm no expert. Just passing along what I learned in my research.
SV South Paw
2000 Hunter 340
South River, MD