How much is a 2004 Troy built riding mower in good condition worth.?

That depends a lot on condition. Some leave grass on which promotes rust, don't change oil or clean the filter often and have rugged terrain and a lot of hours on them so they are worth only $150-200. Others which are clean, lower hours, cleaned up to look like almost new may be worth half the initial sale price, especially if it has had the belts and tires replaced instead of being worn out as those items can cost around $200.

As with any sale of this type you list it priced a little higher than you expect and write OBO for or best offer then see how much interest it generates. The sooner someone calls the more likely you shouldn't budge much on the price. Check your local craigslist for other riding mower listings and their respective prices vs time they have been listed since that is your competition... each season somebody won't sell their mower because it was priced too high for the condition it was in.

$300. It is 9 years old and it probably cost around a $1000 mew.