First off, Optishot was something I've wanted for awhile. I didn't expect to get it until after my Den room was completed. That being said since I live in northern Michigan and there's typically snow outside just after Christmas...... I wanted to be able to play golf NOW. So after I thanked my wife repeatedly I went on a quest to get all the necessary items to get Optishot up and running.
I already had a HDTV so all I needed was a dedicated PC to run the software. I found a used Dell Desktop GX260 with 2 gigs of ram and over a 2ghz processor. I picked a desktop over a laptop only because its easier to maintain, expand and replace parts. It had an integrated video card which was under the recommended requirements so I found a PCI Express video card with an HDMI port. Easily found online, New Egg, Amazon etc. you can find one for roughly $25.
Since I was planning to hook up to my TV and surround sound system I also bought an RCA (white/red) to 3.5mm 6' jack adapter, found at Wal-mart for $6. Oh and I needed another HDMI cable for the video hookup, depending on size they can cost anywhere from $16-$50. Meijer 6' cable $16. The desktop system came with a USB keyboard and mouse but I would recommend getting a wireless set up, at least 2.4 Ghz.. Also could be found at Wal-mart, Logitech / Microsoft each make a pretty good ones, for around $30. Ethernet hook up was next, I happened to have a 8 foot cable but these are typically inexpensive $5 to $10 for a reasonable length. If you don't have the capability to run an Ethernet line a PCI wireless card will do the trick. I plan on getting one of those when I move the system upstairs since I can't run the cable through the finished walls. Wireless card will cost from $25 to $30. Finally since I'm temporarily running the Optishot from the living room behind the couch.. I needed a longer USB cable for the swing pad to reach. I just so happen to have a 4' extension but if you were to buy one there about $5.
So to Summarize:
Desktop PC $30 eBay (2 Ghz processor/ 2 Gigs of ram)
PCI Express Card with HDMI or DVI $25
RCA to 3.5mm jack $6
HDMI cable $16 to $50
Wireless Keyboard/Mouse $30
USB extension cable $5
Ethernet cable $5-$15 / Ethernet Card $25 - $30
So for under $120 I have my system up and running. This will work for now as a temporary set up. I eventually plan to have a dedicated room with 9' ceilings and a wall mount LCD television or a Projector.
For those of you just getting an Optishot, I hope this information helps. Please give me feedback if you have any better ideas or cost savings.