The small parts with that Grizzly mill are worth way more than the mill is. How that mill works for you depends entirely what you intend to do with it. It's a glorified bench top drill press. For drilling smaller holes it would be fine. For milling anything but soft aluminum it would be frustrating.
An IR #30 7-1/2 hp compressor on an 80 gallon tank is $2700 new at Northern Tool, plus tax. I had my eye on that exact compressor for several years at my local Home Depot. Day I went to buy it the store manager pizzed me off, went directly to Blain's Farm and Fleet and bought the exact same Porter-Cable compressor, at the time I was working for a different division of the company that owned Porter-Cable, I had checked with them, F&F beat their price, $1400. I-R at H-D was $1800 back then. No regrets with my P-C, works great for 99+% of what I do. But I wish I had got the I-R.
SON bought a used 5 hp Quincy, 80 gallon tank, pressure lube compressor, a 1964 vintage, was bought new for the tire shop at the Deck truck stop at exit 19, Geneseo, Ill, my old home town. It was sold to a small body shop in Rock Island in the 1980's or '90's, then sold to a small machine shop in Moline about 2005. Son's had to spend some money on it, mostly on the unloader. Place in Moline can get him any part he needs from Quincy next day.
A 7-1/2 hp compressor is marginal for sand blasting. I have a 40# Harbor Freight pressure blaster. Have no idea how guys blast with 5 hp compressor. If I did more blasting I would seriously look at a 10 hp compressor or maybe making some sort of tandem compressor. My 7-1/2 hp P-C runs 100% unless I have a brand new nozzle in the blaster, and then after the first 40# of sand I'm back to compressor running 100%.