The GNS 430 is the single greatest purchase I have ever made for my aircraft.  I would strongly consider getting yourself one of those.  The 430 pretty much tells you everything to do and when to do it.  I had a KLN 90B in the aircraft prior to the 430 purchase.  The time that I spent just to program it and then to understand what it was telling me, hardly made it worth having.   An ADF is a worthless piece of equipment.  I had mine removed when the GNS 430 was installed.  The only thing I miss about it is not being able to listen to AM radio late at night.  If funds are limited, you could probably purchase a used 430 for $5500 on ebay.  Depending on what type of aircraft you have, expect to spend $2,000 to $3,000 for the install. 

If you get an STEC autopilot, I understand that it will even enter and fly the holds for you.  I do agree with Rich, spend the extra money and get alt. hold.  If you decide to go a different route because of money, you can probably pick up a used Cessna 400B for less than a $1000.  It is a solid A/P and most shops can still repair them. 

Good luck

Rich, which shop did you use to have your Garmin 300xl and S-tec 30 installed?  Also, did that price include coupling the AP to the GPS?

We were quoted $11,900 plus installation just to have the AP installed. Needless to say, we didn't take them up on it.