If the annual profit is $50K, IF, there's something seriously wrong with the business if it's not attracting $70K offers.
I'm very familiar with Flippa. I used to be the most active buyer there when it first started (though have only dropped in and out over the years). I've bought and sold numerous online businesses, including script based businesses like yours (sites like
chameleonflash.com,
swfmaestro.com etc) though I no longer do this).
I do not now recommend Flippa, I think they're a bunch of crooks, but fortunately there are many alternatives.
Income on average $1500-$3500/month (sometimes $5000-$7000).
An average is "a" number, not a wide range, certainly not multiple ranges!
Your annual profit figures don't make sense. At the bottom end of your range, the $1,500 pm, the annual revenue is $18,000. How did you get an annual $40K profit out of an $18K turnover?
At the top end of your range, the $3,500 pm, the annual revenue is $42,000. How did you get an annual profit figure of $50K out of that?
You need to get smarter with numbers and your presentation of numbers. I asked you for an average profit and you blabbered on without giving me that one simple number! I'm no smarter now about your earnings than I was before your post.
Buyers don't like dealing with people who don't understand their own numbers. It's not a buyer's job to wring things out of you. I personally would drop a seller the moment I realised he was clueless on the numbers, it's just too much hard work dealing with sellers like that. If he can't give me even basic info on financials, he's going to be a nightmare when I start talking TTMs, churn rates, referrer stats, whatever.
Also, all this fuzziness with accounts makes you look dodgy! I recommend talking to an accountant or someone to tidy up your figures, explain revenue and profit, explain gross profit vs net profit etc etc, and put together some professional looking figures.
One last thing, if your average monthly revenue is $1,500 pm, that's $18,000 in turnover, obviously less than $18K in actual profit, and you may need to start by putting your $80K valuation in the bin.