what is the item for 3gp and sell it for 70+ gp with unlimited supply?

it called "Next Video Converter". It is easy to use, you only need click few button.
Next Video Converter is a free video converter and DVD ripper with easy-to-use graphical interface, fast converting speed, and excellent video quality. It can convert almost all video formats including DivX, XviD, MOV, RM, RMVB, MPEG, VOB, DVD, WMV, and AVI to MPEG-4 movie format for iPod, iPhone, PSP or other portable video device, MP4 player, or Smartphones.
It can also rip DVD to any video format.

Make video for Sony PSP portable video players with PSP video converter.

I think 4Videosoft 3GP Video Converter is the first choice for you to convert video formats, for it supports MPG, MPEG, MPEG2, VOB, MP4, RM, RMVB, FLV, MPV, MOD, MP3, MP2, AAC, etc to 3GP, MP3 for all the brand-new phones: BlackBerry, Google Phone, Nokia, Motorola, Samsung, etc.
After doing the steps above, you can click “start” button to start conversion.
Try Leawo Video Converter which can convert videos and audios with video editing fucntions. leawo video converter can convert videos and audios between popular formats: AVI, MOV, MP4, MPEG, WMV, MOV, DivX, Xvid, VOB, ASF, MPG, MP3, WMA, 3GP, RM, RMVB, DV, TS, etc. and it can crop, trim and merge video files.

Mac DVD ripper could rip DVD to AVI, multiform videos/audios
Rip DVD movie to video and audio formats including AVI, MPEG, WMV, MP4, DivX, H.264/AVC, MOV, 3GP, 3GP2, MP3, WAV, WMA, AC3, M4A, OGG, RA, AU, etc.

you can even use this leawo video converter to Burn videos to DVD with DVD menu. Get Leawo video converter here.
Inputs: WMV, WMA, AVI, MPG, MPEG, RMVB, RM, RA, MOV, QT, MP4, M4V, DV, DAT, MP3, AAC, etc.
Outputs: 3GP, 3G2, MP3, AAC, WAV, M4A, etc.
It is free with no limitation and easy to use. You can try, and here are some steps.
1,open the program, click add to find the video you want to convert.
2,setting. choose the mp4 as output format, and the folder you want to save your mp4 video in.
3,click start then wait till the process finished.
4,when you got the mp4 video, you can drag and drop it into the video folder in your mp4 player.

DVD to MP4 Converter is excellent DVD ripper software, which can convert DVD to Zune/iPod/PSP/MP4,MP4 AVC Video.

I think this guide may can help you too.
Because it has excellent quality and fast speed. It can convert video and audio files with comprehensive formats as follows:
Input formats: WMV, ASF, WMA, AVI, RMVB, RM, RA, MOV, QT, MP4, M4V, 3GP, 3G2, DAT, MPG, MPEG, MP3, VOB, DV.
Output formats: AVI, MPG, MPEG, VOB, MP4, 3GP, 3G2, MOV, WMV, FLV, DV, MP3, AAC, M4A, WMA, WAV, AC3, MP2.