Hi.
I think you will find that as they go higher in generation (away from the ALC), they become cheaper, until you get to F4/F5 and they are then standard SBT price.
An F3 should be priced somewhere between the F2 and F4......less than F2 but slightly more than F4, but quality being taken into consideration as always.
Re...your other question: "I'm hoping to find a super outgoing kitten, one who will like to go out on adventures on a leash, really interactive and very affectionate. Would this be a reasonable expectation from an F3?"
I am not sure than F3 would be the best for this as the EG's can be more reserved and slightly shy sometimes, so maybe wouldn't make your ideal 'harness/outdoor/adventurous' cat. I am sure there may be exceptions to the rule but you would be lucky to find one that would be happy doing this, I think?