Well, I've had one axial 28 Spec 1 (the first axial 28). Was easy to break-in, held a decent tune, had ok power clear up to about 1.5 gallons. Then it became a piece of garbage. Ran horrible, no power, started easy, idled all day, but sucked otherwise.
That's all I'll say about it.
LRP28S3 is a great engine. However, $165+ is over your budget, especially if you include shipping or tax if you buy local. Then your closer to $180.
I ran a STS D30 and it was similar to the axial... but ran like crap pretty much from break-in to about a gallon. Never improved, only progressively got worse. Sold it with the axial just so I could stop looking at them and getting angry.
I heard the STS 28's were pretty good. A bit hit or miss as to if you get one that ran well though. So, kind of a gamble. Either you get a ripper or a dud. However, that was with their first making of them. Then they relieved the pinch a bit and the hit or miss percentage became greatly better. The D30 was built really well, but like I said, a dud.
The Dynamite Mach 28 is somewhat of a dud for it's size. Low rev's, decent power output, but not on par with many other 28's.
The dynamite 427 gold head is a good engine as is the green head (larger carb venturi, faster of the two supposedly). I've seen 3 gold heads and one teal run and all of them were decent performers that had a decent life span. Even in the hands of newbies.
I've seen a few of the HPI 4.6's and they do have decent torque, but lack severely on top end RPM's IMHO. Every time I watch a vid of one or see one running locally, I keep wondering if they are holding the throttle at 2/3's open.
$150 or less from my personal experience, Mach 427:
http://www.amainhobbies.com/product...mite-Mach-427-Pull-Start-Monster-Truck-Engine
From what I've read:
STS D28M
Go 28
Although... Dynamite just made another 28... BIG RED:
http://www.horizonhobby.com/Products/Default.aspx?ProdID=DYN0992
May be a contender for a basher as well.