If you'd like to save some money you can do the DIY Fat Tire conversion and you have two choices if you go that way.
8" rim / Dunlop Elite III 240 / very minor swingarm modification
8-1/2" rim / Metzeler ME880 240 / addtional swingarm modification
To elaborate some on these, both swingarms can be modified by you so the only thing you need to send out to have done is the rim. According to factory specs there is only 3/16" difference between the widths of the two tires with the Metz being slightly wider. Cost wise the Metz will cost you about $70 more. Wear wise I've had very good luck with the Dunlops.
SWINGARMS: The swingarms will require some stock removal. Most guys do this with an angle grinder. The 8" rim/Dunlop requires very little removal. The 8-1/2"/Metz requires quite a bit more. Some members feel that the swingarm requires some rewelding after doing clearance for the Metz, but others have done it with no ill effects.
TIRES: The difference in the tires is as follows: The Dunlop has a more round contour and will give you handling that's a bit more like stock. The Metz is a flatter profile. Mileage is similar.
WHEELS: There is no cost difference to modify to 8" or 8-1/2" wide. The only variables is the finish. Kosman Specialties does an excellent job on these and many guys choose to go with the "raw" wheel. That is a wheel that has been welded but the welded bead is not smoothed out or removed. It will save you about $200. Mine is done like that and it looks fine. The bead is so uniform that is actually gives the wheel some character. The only time I would remove it is if I was going to chrome the wheel.
SUMMARY: You can do the DIY Fat TIre Conversion (with raw wheel) for between $800 and $950 depending on which wheel/tire combo you choose.
PS: If you are lowering your bike I'd recommend a 1000 lb Eibach spring or larger. The stock spring is a bit weak and could cause you to bottom out.
God first . . . . . . . . always!