GM,
I will not go further into homebrew interface as it was already mentioned and not sure you want to go that route but it would be the cheapest.
I agree with the other op that mentioned the SIGNALINK interface....if you are serious about digital modes then the SIGNALINK USB w/built in soundcard is the way to go - works very well and highly recommended.
Since you want cheap and easy and not sure you will like digital modes then you might try the Donner interfaces - they run $40 bucks brand new and if you end up not liking digital modes sell it back to someone else to try for $25 to $30 to regain most your money invested back.
http://www.eham.net/reviews/detail/2073http://www.donnerstore.org//index.php?main_page=index&cPath=94_99_111http://swap.qth.com/RADIOHF - DONNER DIGITAL INTERFACE-ICOM
A like new Donner digital interface control for 8 pin Icom radios i had it hooked to a ProIII,but will work with all 8 pin port radios,30.00 free shipping,U.S.sale only,money order only,no pay pal.
Listing #1086374 - Submitted on 09/03/13 by Callsign AG5RP, Modified on 09/07/13 - IP: d-24-245-123-87.cpe.metrocast.net
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MISC - DONNERS DIGITAL INTERFACE !
SELLING A DONERS DIGITAL INTERFACE FOR ICOM IC 746 PRO.NO LONGER NEED IT . NO ISSUES. $30.00 SHIPPED CONUS ONLY.POSTAL MO OR PPAL + FEES.THANKS FOR LOOKING.73.
Listing #1085713 - Submitted on 08/31/13 by Callsign 3055820046 - IP: c-98-254-1-26.hsd1.fl.comcast.net
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DIGITAL - Donnar Digital Interface 8 pin ICOM
Used very little excellent condition $25 shipped Conus, Paypal accepted.
Listing #1082900 - Submitted on 08/16/13 by Callsign KA1GM, Modified on 08/25/13 - IP: cpe-74-78-39-11.maine.res.rr.com
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Keep in mind there are other commercial interface units (MFJ, RigBlaster, etc) but those are going to run even used more than the Donners interface unit - most those used is from $50 to $90 or so - although you might find a RigBlaster No-Mic used from $25 to $40)
GL and hope to work you in digital modes (if you have digital mode questions or need help to get started email me direct if you would like KB9UMT AT ARRL.net or KB9UMT AT 30MDG.net)
Don KB9UMT
30MDG#0001
www.30mdg.net