I go by what I've seen him sell for with his hat. I bought him with his hat in NM for condition for $8...lol... And I see his hat sell for $10 often.
You would be surprised. The big brothers don't go for as much as you think. I keep tabs on eBay. I'll see an excellent condition Chief go for maybe $15 one day and then another excellent condition one go for $5 the next. So then that averages out to $10. It's up and down and crazy sometimes, but the averages are lower than you think.
As for Slugger, his hair is frizzy, it's faded to white, he's definitely not in near mint condition for that sheer fact, I'd not put him anywhere near the $50 range. By himself without the hat, he'd be hovering around $10-$15. Add the hat, and you add another $5-$15, depending on what the market is doing. You'd have to add a bandanna and a brush to put him anywhere near $40, in fact.
Maybe I low-balled him at $20. Maybe $25-$30 is better, but that hair really bugs me. And not being able to see his hat in the photo bugs me even more.