I fitted a Sidepower SE40 thruster about a year ago but have only just got back out in the boat. It took me about 8 days solid to fit it my self and about £1700 ( £1100 for the thruster, £400 for lift out and £200 for epoxy/cloth/matt/bonding fillers etc). After 10 days sailing each day and 6 different marinas I could not be more delighted. It just takes all the tension away from entering strange and sometimes tight marinas and worrying about getting in, getting out and having difficult situations due to the more limited manoervering of a cat with an outboard. Maybe my handling skills are not the very best but I have never hit anything in 14 years with this boat but the bow thruster was a revelation, it makes such a difference just a touch here and there with the thruster.
I was concerned I was wasting my time but it is great.