if I buy an ultrasonic cleaner for my records will I be able to hear the difference?

I own the V-8 and it certainly does improve the sound of records. It opens them up considerably. But as I've posted elsewhere, the GEM Dandy Record Cleaner did a considerably better job for a far more significant drop in price. For older and damaged records, I found the Groove Lube to very helpful at reducing the sonic effects of the damage. It does leave some residue on the stylus that can easily be removed, but you have to carefully follow instructions and use as little of the Groove Lube as possible and buff the record carefully after spraying on the pads, rubbing them and applying the treatment. 

+1 pbnaudio
i have the same set up. It’s made 40 year old lps, that I took great care of from day one, come to life. Who knew what micro dirt could take out of the music?
amazing
flea market records can still disappoint, but not nearly as often. Makes taking a chance on a $5 copy of Europe ‘72 a good gamble. 
Takes a bit of work to do it right but you only need to do it to disk once. And a good anti-static brush is all you’ll need.  
You’ll find an excellent formula for the bath here on Audiogon, Audiokarma or several other sources. It takes a bit more than just distilled water to get it right. Go for it.

I've heard of "clubs" forming to purchase and share the high end cleaners.  You pool your money, purchase the unit, and each "member" uses it for a week/month then sends it to the next person.

No question it will work. I bought the cleaner vinyl adapter and ultrasonic cleaner about 6 months ago...cleaned all of my several hundred records. It made a notable difference.  They play much quieter, surface noise was greatly reduced. I figure I spent about 300 for the adapter (2 record version) plus ultrasonic unit.  I used a very small amount of Dawn plus photo flo in distilled water.

My first record cleaning machine was KAB's version of the Nitty Gritty. When my friend bought a Keith Monks machine he gave me (!) his VPI 16.5. I have cleaned records using all three of these and have found that when used properly there is no difference in sound between them. All produced clean, quiet records. If you purchase a lot of cruddy used vinyl, an ultrasonic unit just might be better. The more money you spend, the more the machine will do for you.