What record cleaner is the most bang for the buck??

I've been using a De Stat Gun and Discwasher for over 45 years. I borrowed a friends UC and cleaned my 1600 pieces of vinyl. About 500 are from other peoples collections and most were filthy even after the Discwasher. The UC cleaned most of those up completely. The rest of my collection is new vinyl I have purchase for the last 50 years or so. They have all been de stated and then Discwasher before each play. They showed little to no gain from UC. 

My cleaning solution is now 1 qt. distilled water and 25 ml pure Isopropyl Alcohol.

+1 I prefer ultrasonic cleaning. Once is enough, after that take reasonable care of the cleaned records and just use a brush if necessary

I recently bough an Audio Desk used. I have very few used records, and quite a few higher-end pressings. I just completed cleaning all 350 or so. I’m really surprised at how much better they sound.

Once cleaned with US, there is no need to use anything other than a brush - I use the Audioquest carbon.

Prior to this I used the SpinClean - it does an OK job but there is no comparison to US and the manual process is a pain. 

Lastly, I don’t understand what a dust cover has to do with this question.

I use ultrasonic record cleaner

1+ Okki Nokki

I use this stuff made buy Bugtussel called Vinyl -Zyme Gold. I find it to work really ,really well. Been using it for many years ,like 20 and it never ceases to amaze me.