Here is one original accessory for your iPhone. It’s a speaker amplifier in the shape of a horn. Best part of it is that it doesn’t need any batteries as it takes advantage of the horn to naturally amplify the sound coming out of your speaker by adding up to 12 decibels.
Horn Stand Amplifier Speaker for Apple iPhone. Effectively enlarges music from your iPhone. No external power needed, 13 dB of volume amplified. Holds iPhone vertically and horizontally, functions well in hand-free mode.
You can get this amplifier for $2.22 from PORTABLE AMP FOR IPHONE HORN STAND BLACK (PORTABLE AUDIO/CELLULAR ACCESSORIES)