as far as tube vs bar & plate goes, ive had both. i bypassed the stock cooler (basically heater) and ran just a tube style which ran hotter than the stock setup, heat soak was instant. now with a roughly 12 x 10" bar and plate it runs 185-195* constant, unless im in stoplight races non stop.
as far as pricing you can make a kit for under $100 all day, the cooler at most is $50-60 and some hose and clamps cant possibly be $40. Anyone in the Dubuque, IA area that needs a Cooler let me know, I got some Ill sell for damm near nothing, like $20. never used on a running transmission, just had fluid through them as they came on rebuilts we get