Chapin pump sprayer from Walmart is $5. ONR is $55 for one gallon on amazon (wash+wax instead of just wash), which is good for ~200 washes (more or less depending on your dilution and use). Big microfiber towels are $6 for 3 on AmazonBasics. The mitt for washing on AmazonBasics is $5ish. China washing mitts are too small for European hands, but they are less than $1 each. I went with AmazonBasics for the mitt. Grit guard from china is ~$6 each -- get the smaller diameter, 23cm vs 26cm, one so you know it fits for sure. Get buckets from Lowes or Home Depot for $5 each. When you read China, read 30 days for shipping.
If you experience bird poop or something like that, like salt or big bugs, go to a self-service car wash where you can power wash off the crap before ONR. Or just do a touchess carwash before ONR for about $7 a wash, which is the most basic wash at my local touchess carwash.