50-60 adjustable pump in home depot
 

-I found a 50-60 adjustable pump in home depot (also saw the same pump at Lowe's and a local garden shop) for 20$. This works great for my larger systems. I also found a timer that can be set as low as 15 minute intervals for 10$ at Walmart.

What type of pump is used for the top drip system? I am assuming that a top drip system would have a very low GPH flow. Where could I find one of these?

Same kind. A larger GPH submersible pump can be used with smaller gardens with a flow control valve to lower the (gallon per hour).