That is very dangerous. You better have some idea,before invest in it. Generalization,flipping website is buying website than have potential to earn more,optimize it,then resell it for profit at 3x of the purchase value.
website flipping is basically creating a useful blog/website and then selling it. Just like buying furniture for your hosue, your house valuation increase
Make useful and attractive site, get visitors approximately 1000 uniques /month, get revenue for about $50/month from it, then sell it for 3-4 digits $