The amount of what a bit is worth more often gauged by the maker. For example, a Tietjen even though is a stainless steel bit is worth more than the bit pictured above just because who it was made by and the maker is dead. Mouthpieces come into play as well the bit above has what is called a frog, not very popular, if it had a half breed it would sell easier and for possibly more money.
The Les Vogt performax bits aren't worth anymore than what you pay for them because they are a mass produced bit. But if you had the same cheek design and mouthpeice and it was made by Grijalva, it would be an $800 bit.
Same with Garcias, a Paul Garcia isn't worth a whole lot, but you have the same style bit that is marked E. Garcia is worth more or if it is marked Garcia Elko Nevada.
Just because it is silver doesn't mean it is worth money. Also these style bits come in either Sterling silver, nickel silver,engraved monel, or engraved stainless. Knowing the difference between the materials helps but knowing makers and mouthpeices and cheeks are more important
I DON'T LEAD 'EM AND FEED 'EM, I RIDE 'EM AND SLIDE 'EM.