In Hudson County it’s unrealistic.
Somerset has opportunity
If you are buying at Sheriff's Sales in New Jersey, you will need the full amount in cash to close and at least 10% in the form of a cashier's check at the time you win the bid. You have no chance at all to do anything in Hudson County at auction with 20k cash. Any other private auctions in Hudson will still be cash friendly even if mortgages are allowed and will likely not have what you are looking for.
The real question is what are you trying to do with the 20k. Use it as a downpayment to buy what? A hold property where your cash flow is positive? Why Hudson? It is completely on hire with investors and buyers.
When the bid starts at $100, that usually means that the bank is buying back the property in order to re-sell or auction it again. You will not win a property when the bidding starts at $100. I look for auction properties that have real starting bids, in the tens of thousands. Those are the ones you can actually win. I always visit properties before bidding, to get an idea of what repairs are needed and ARV (after repair value). Also do whatever other research you can, pull permits from the code office to see what repairs have been done in the past and what might need to be done in the near future, look at tax maps to confirm property size, check comps (Refin is good for this). With 20K in cash, you could maybe partner with another investor just to get started. Unless it is a very low priced property or you have good W2 income, you are unlikely to get a hard/private money loan with that amount of cash to bring to closing.
Join the Largest Real Estate Investing Community
Basic membership is free, forever.