Good question, There are many answers for you.
I have been selling internet Based Businesses and flipping eCommerce stores for the last 13 years! There are so many reasons why Flippa is NOT working these days. But aside from the buyer pool that Flippa has, it boils down to what you are selling & Who are you targeting when you post a listing.
Your Listing info is going to be your first step on getting an interested Party to reach out to express their interest in buying something. Really if your looking to sell something that is 100% legit. These are the things that will help you. If your selling a start-up website that doesn't have much history behind it. You're not going to get much for a sales price and you'll most lilkey sell it to something who is new to the space.
---YOUR SITE WILL SELL IF---
** You have a good website look and feel for the buyers
** Must have a decent Background on financials, Preferably at least 6 Months min. of regular sales that are stable or growing regularly.
** A website that has Organic Sales through unpaid avenues are going to really help make your site sell fast. ANYONE can build a website these days and just start doing google adwords and buy adverts through all the other places, Make money through sales and move on from there. Organic everything is HUGE and will make you stand out.
There are so many other things I can that will help you and I'm totally open to talk with everyone one-on-one if you'd like too. And if your looking for some help, let me know. I just so happen to have REAL buyers list of phone numbers and emails of around 56,000 people right now, these are all people that I have personally talked to over the years. This list itself is such a big thing haha.
I am totally open to helping you out if your interested.
Hope everything works out for you. Cheers!