I bought two barreled actions, one with a heavy varmint barrel in 223 bedded in a Bell & Carlson stock and another I bought December, in 308 with standard barrel (which I intend to remove and replace with a 6mmBR or 6.5x47 aftermarket barrel).
I have done lots of research on the Howas, and there is much to like (flat bottom receiver, integral recoil lug, long action screw engagement, one piece bolt (not brazed), forged action and bolt, M-16 style extractor, vent holes in bolt directed to mag well, bold disassembly without any tools, 3 position safety, and as you found, cheap).
Since you are interested in aftermarket, there are Timney triggers available. Note recent Howas use the HACT two stage trigger, while earlier models use a single stage.
http://bulletin.accurateshooter.com/2011/12/howa-offers-upgraded-2-stage-trigger-plus-dbm-conversion-kits/
Depending on your expectations, the Howa triggers are often seen as better than most. A Timney will no doubt be best.
If you want a turn-key bolt, see Pacific Tool & Gauge. http://www.pacifictoolandgauge.com/howaperformancebm.htm
More stuff here. http://www.webshop.roedale.de/index.php?cat=c125_Howa-Tuning.html Navigate around on this site. There are mag kits (which have a design that is preferred to some of those made here in the U.S.), as well as one chassis kit, and another one upcoming. The person who runs this place is Pete Lincoln and can be found on Snipers Hide. He is an ardent supporter of Howa and can tell you a LOT.
Short Action Customs sometimes has trued Howa actions on the shelf. Most will tell you the actions don't need much truing and are quite accurate to start with.
For my 223, I bought the Howa detachable mag kit. A very lightweight polymer trigger guard (not heavy duty, but fine for me), and 10 round detachable mag for a grand total of $97. Cheap, it takes literally 90 seconds to install, and it works.
Stocks are harder. XLR and Roedale make chassis. Bell&Carlson, McMillan, Manners, all make stocks, and StockysStocks often has some Manners in stock, with no waiting. Either for stock Howa inlet or CDI mag kit. There are some laminates you can get for the Howa.
Standard Remington two piece bases will fit, but a one piece is Howa only. I bought mine from Murphy Precision. Stainless steel (black) or titanium. Very nice piece. Threads are American, not metric.
Barrels must be cut with metric threads. Some people recut the Howa action and barrels to American, but I personally would not do that.
Speaking only for myself, I very much like the Howa, and while I did just acquire a Savage, it was only because it presented some features no other action in that price range could offer. For everything else (that is not a custom action), it is Howa for me.
Note, Howa is revising their distribution model in the first quarter of 2014. If you want one, and are having difficulties, please PM me. I am not an FFL.
http://www.snipercentral.com/howa.htm (pretty sure this has the older trigger).
Phil