In a way, Dev, CalStar does offer 'previews', in the series they call 'Footloose & Featherbound'. These are short sequences from many of their videos, but the only 'F&F' I have didn't show what Vids the clips were taken from. Years ago I called and pointed this out to them, but I don't know if they heeded the suggestion to add titles to each sequence.
If you are bound and determined to try one or more of Calstar's tapes, here's my recommendations: Tied & Tickled 8, 10, & 13. (If you like 'gorgeous Greta Karlsen, aka Barbie Lyons, T&T 8 & 13 feature her.) Of the other later vids which have names like 'Frankentickle', 'Alice in Tickleland', etc., the only one I could really recommend is one called 'Members Only'. It's full nudity with Jewel Marseau and another model tickling each other. As the story line on the site provided by TKpervert points out, Jewel does seem to get genuinely aroused by being tickled - to the point of showing wetness. So, if nude tickling scenes are your thing, that's a good one, in my opinion.