So 30 blocks will go together nicely with 5 x 6 blocks. For sashing, to make it easy, use a jelly roll or a moda solid. You can buy those on sale for $18 or $20. Use a fun print that coordinates for the corner blocks of the sashings -- a fat quarter is plenty. The backing -- I don't know what you have in mind, but I think I could do that just fine with 4 yards of fabric, running say $5 / yard. What are we at now? Under $50.
Yes it will take time and some aggravation, but it's not as bad as you are making this project out to be.
RST