Greetings,
This document may prove a useful guide to the various capacitor types available.
The polar/nonpolar question is one to start with; like microwave cheeseburgers, nonpolar 'lytics do exist but have many less than appealing qualities…
After that constraints on acceptable C, V, and $ values narrow the options quickly. 5kHz is no longer fast for many 'lytics (polymer types particularly), films rated for 600V won’t protest if operated at 6V, and increasing frequency by a decimal place or two will likely require the question to be revisited all over again, not leastwise because many devices sold as capacitors are actually inductors at higher frequencies.