Make them yourself. Use iTunes. On the song, go to get info. Go under Options (the start and end times) Select the 30 or so seconds of the song you want. (You may want to try a few times.) Then go to Edit-Preferences (You can use Ctrl+,). Click Import Settings. Select Import Using MP3 Encoder and whatever quality you want.
Then right click on your song that you welected the seconds of. Click make MP3 version.
It will appear in your iTunes folder under that artist.
Email it to your phone (as an attachment) using the chart below.
(Chart copied off http://www.makeuseof.com/tag/email-to-sms/)
Alltel [10-digit phone number]@message.alltel.com
Example:
[email protected]
AT&T (formerly Cingular) [10-digit phone number]@txt.att.net
[10-digit phone number]@mms.att.net (MMS)
[10-digit phone number]@cingularme.com
Example:
[email protected]
Boost Mobile [10-digit phone number]@myboostmobile.com
Example:
[email protected]
Nextel (now Sprint Nextel) [10-digit telephone number]@messaging.nextel.com
Example:
[email protected]
Sprint PCS (now Sprint Nextel) [10-digit phone number]@messaging.sprintpcs.com
[10-digit phone number]@pm.sprint.com (MMS)
Example:
[email protected]
T-Mobile [10-digit phone number]@tmomail.net
Example:
[email protected]
US Cellular [10-digit phone number]email.uscc.net (SMS)
[10-digit phone number]@mms.uscc.net (MMS)
Example:
[email protected]
Verizon [10-digit phone number]@vtext.com
[10-digit phone number]@vzwpix.com (MMS)
Example:
[email protected]
Virgin Mobile USA [10-digit phone number]@vmobl.com
Example:
[email protected]