Some translation help please

Hi, I was wondering if someone could please help explain the meaning of the following to me: 土日祝休業。Amazonのみ出品、品切れなし ビニール+プチプチ+封筒にてしっかり梱包

Here is the full context, in case it helps:
土日祝休業。Amazonのみ出品、品切れなしビニール+プチプチ+封筒にてしっかり梱包親切・安心対応、そして迅速で確実な配送を心がけております盤面、ジャケット(歌詞カード)、ケース状態良好

I have been trying to parse out the meaning of this whole thing with a combination of a Japanese-English dictionary, running it through an online translator, and asking my friend (who is a beginning Japanese language student) However, I'm still puzzled by the part I quoted above. I would really appreciate any help. Thank you so much!!!

土日祝休業。Amazonのみ出品、品切れなし ビニール+プチプチ+封筒にてしっかり梱包
Closed on weekends and national holidays. Goods listed only on Amazon - thus will always be in stock. Goods will be securely wrapped in plastic, protective "bubble" wrapper, and placed in an envelope.

What they mean when they say "Goods listed only on Amazon": some sellers have their own shops outside Amazon where they list the same merchandise, so that even when you place the order through Amazon, they get back and tell you "sorry it's out of stock, it just got sold elsewhere." This seller is saying that that won't happen, because he/she is only selling on Amazon.
"プチプチ" is those... protective "bubble" wrapper sheet :) "puchipuchi" is the sound when you pop it for fun :)

Thanks a million AK!!! That makes SO much more sense now. Thanks again!!!