With a $500 budget you have three options: The best one is the one that is best for you. How much convenience do you want, how quiet do you want the process, how long do you want it last, what are you cleaning - only new records, or are you going to be buying used flea-market. But let me emphasis one item, any of these can achieve a clean record BUT, BUT, BUT the devil is in the details.
1. For about $250 with all materials and cleaning agents, manual clean using a record label protector such as the process specified in Chapter 5 of Precision Aqueous Cleaning of Vinyl Records-3rd Edition - The Vinyl Press. This process can clean any record of any condition. But it is fully manual, and the success is based on your technique but it's a short learning curve and there is very little to wear out.
2. For $500 you can purchase a vacuum-RCM. There are a number of variations available, you want one with the suction tube/wand on top of the record - they are the easiest to use. Vacuum-RCM at this price point will be very noisy and they are still manual clean - the chemistry you use and brush you use and how you use the brush will determine how well the record will be cleaned. The benefit of the vacuum-RCM is speed - faster to dry. However, if you dry too-much you will develop static - it’s that devil is in the details (but short learning curve). The durability at this price point can be 3-5 years but choosing one with good OEM support will allow long term use. The suction wands and the Velcro heads need to be periodically replaced. Vacuum-RCM can be used to clean used records with the right chemistry; pre-clean, rinse, final clean, rinse such as specified Chapter XIII - Precision Aqueous Cleaning of Vinyl Records-3rd Edition - The Vinyl Press.
3. For $500 you can purchase the HumminGuru all-in-one ultrasonic vinyl record cleaner. This is not a bad unit when used correctly (remember, the devil is in the details) with this being the best procedure to date: HumminGuru - an inexpensive desktop RCM | What’s Best Audio and Video Forum. The Best High End Audio Forum on the planet! (whatsbestforum.com) - see post #62.
The durability of the HG is unknown, it’s still relatively new but with light use, 2-3 years should be appropriate. The OEM is in China, but support appears so far to be decent. There is an active thread over at Interesting All-in-One Ultrasonic Cleaner - HumminGuru | Steve Hoffman Music Forums. The HG is not great for used records. You will need some form of pre-clean step and people often use a Spin-Clean. However, the HG is very convenient, and is relatively quiet and very compact.
4. For $500 you can put together a DIY ultrasonic tank cleaning system starting with the cheap 40kHz UT now available - Amazon.com: VEVOR Ultrasonic Vinyl Record Cleaner 6L 40kHz Vinyl Ultrasonic Cleaning Machine Knob Control Record Ultrasonic Cleaner 4 Records Vinyl Sonic Cleaner Stainless Steel Tank w/Mechanical Heater & Timer : Industrial & Scientific. To make these work, there is a lot of details, and they will not work very well unless you nail the details. The PACVR Book Chapter XIV has some 40 pages discussing all the details.
Beyond what is addressed above, and what is written in the PACVR Book, there is no lack of information on the web with some 50 different cleaning products all saying theirs cleans the best. There are those that swear-by PVA-wood glue method, and some even use steam cleaners.
It’s a carnival of options, but I will end this as I started it, the one that is best is the one that is best for you, but most any of them can be made to work effectively but make no mistake, the devil is in details.
Good Luck!