Here's what I keep coming back to every time I start considering buying them. On realtree's nursery site, it says in 10 years they can produce 10-25 lbs. Now, you know the numbers they are using are in ideal conditions and they are talking top end range. So, if I plant 10 of them, in 10 years, I'd be extremely lucky to produce 100 lbs of chestnuts. Now, $300 isn't a bank breaker, but, for the time and $300, I can do a lot of stuff that will produce a heck of a lot more than 100lbs of food, and I won't have to wait 10 years to see those levels.
That said, I'm extremely tempted to grow a bunch from seed and likely will start on that within the next few years...$20 for a lbs of seed I can see being worth it, just to add another attractant, even if it will never be enough to make a big nutritional difference.
Just my thoughts/how I work things through in my twisted little mind.