Cheapest way to ship large speakers?

A good friend!

I shipped soundlab m2's from Seattle to southern NJ
on united van lines;no problems encountered at all.

I used a company called R&L to ship my Dyn C4s 2000 miles with no issues.Used they a couple of times and they are great! Quite affordable as well.As far as UPS/ FED EX goes I would avoid them at all cost.I bought a sub about a year ago and it was shipped through Fed Ex.I happened to be looking out my window waiting for delivery when I saw the driver pull up,open his side door and push the box out onto the sidewalk with his foot.

I just shipped a pair of Totem Sttaf from Boston to Geneva, Switzerland with my sister in law as excess baggage on Swiss Air. They were 2 boxes, 30 lbs. each. They charged them as extra suitcases, at $25 each. They should have charged more as oversized, but they just charged as bags. Even if they had charged their regular rate for oversize luggage ($200 per box), it would have been cheaper than other shipping options. The boxes had Swiss Air Fragile - Glass stickers on them, so I think they were treated pretty well, unlike Fed Ex who dropped them hard enough to break the magnet off one of the tweeters and break a solder connection in one of the crossovers - in just getting them from Philadelphia to Boston. This is probably not an option here, particularly because of the size, but it is something to keep in mind. It worked well in my case.

I recently used YRC to ship a 250 pound skid containing speakers from Montana to Illinois. Yellow and Roadway Freight merged to form YRC. The cost was only $350 (I saved $150 by going to the local Illinois warehouse to pick them up). YRC made everything easy easy easy.