Werks B5 /
2058 tower always runs deals I got my combo for $275 with a $25 off of $300 coupon... You MUST get the pipe to match the ones that work best are the 2058 and 2013
Werks Racing has been around for quite a while and they are known for their super cheap (price not quality) Italian made mills. They are manufactured by LM, the same company that manufactures Serio and Orion.
There are a few pages on the engine
here
Short answer the B5 is one of the most popular engines around right now...