$300 sounds about right. I've seen a surge of Lyle guitars lately on Craigslist and eBay. 
Blue Book maxes out the low end models of Lyle guitars around $225, while the higher end models max out around $400.
By maxing out, I mean it usually includes a case, and the guitar has a 95% condition. No major gouges or scrapes, original accoutrements, etc. 
Of course, then there's the eBay factor where things can multiply about 50% if you take really good photos and generate a buzz. 
 
Good condition are roughly half the top price.