A simple request---Please pack audio gear well.

there is extensive instruction in the FAQ section:
http://www.audiogon.com/cgi-bin/faq.pl?Sellers/Shipping&&actg

Who paid for the shipping? If the buyer agrees to pay the shipping costs they are in a much better position to specify how the equipment should be packed and sent. If you want it double boxed and no-peanuts, then make it part of the deal.

Respectfully, everyone should read the FAQ guidelines I referenced above. They are detailed, specific, and if followed will mitigate pretty much any problem that comes up. Per the guidelines, who pays for shipping is negotiable (ie buyer or seller will pay), but irrellevant to the question of who's responsible for safe packaging and shipment. THAT, is always the seller's responsibility. I personally will not deal with a seller who doesn't subscribe to this rule.

My earlier question about who paid for the shipping costs goes to the point of "you get what you pay for". If how the item is packed is important to you, and I can't imagine why it wouldn't, then you should be very precise in your purchase offer to specify your requirements and may be even go so far as to back it up with dollars. Sure it's the seller's responsibility to adequately pack the item, but as a buyer do you only want an adequately packed item? Again, if it's important, then specify in detail and pay for it.

. . . an excellent point, and I think this approach is necessary because we've seen that few sellers bother with attention to standards such as those published on the site. I've purchased from sellers with extensive + feedback who shipped items with entirely inadequate packaging. It was left to me to wait for settlement of claims.

Regarding UPS packaging - I've received several shipments packed by ups stores and NONE of them were packaged adequately to withstand UPS's normal handling. They used bubble wrap for a 70 lb Rel subwoofer for cryin out loud! There are only 2 shipments that were packaged by a UPS store that didn't sustain some damage. 2 others were total losses. In one case (Rega Speakers) I asked the seller to ensure the packaging was "bullet-proof". He had the UPS store "add some extra padding" to the original mfg shippping cartons. UPS tossed in some peanuts and bubble wrap (literally tossed, and it was not enough to fill the box even half way). Those speakers arived damaged because the mfg carton was pretty worn down and had too much give.
you cannot use bubble wrap or peanuts for amplifiers and speakers!! This is how heatsinks and face plates get bent. You also can't ship in single wall boxes - which apparently is all the UPS stores stock.

One thing I do to assess what kind of attention a seller will give to packaging is to read the feedback comments. If there are are comments like "great packaging" from most buyers, I'm usually comfortable. If not, I spend a good deal of time specifying the kind of packaging I expect.

Tvad, approx how much is the upcharge? (ie as a % of bill)

Bubble wrap is great for light components, but alone isn't enough for heavy amps or speakers. Their corners will cut right through it and be destroyed the first time the package is drop-kicked. I've been the recipient of amps poorly packed in bubble wrap. Speakers too.

I have found that the solid foam insulation from home depot is great. it comes in various thickness (1" - 2") and also different densities (white vs pink). They sell it in panels 2ft x 8ft for anywhere from $5 to $12 depending on thickness and type. It also comes in 4ftx8ft size. It cuts to size very nicely.

If I use peanuts, I put them in a poly bag and seal it up with tape. It helps prevent shifting, and is also much friendlier to the receiver.