A few items from Georgia...
When I bought our '94 Class A, all of the cabinet doors rattled incessantly while traveling. I picked up a package of felt pads at walmart (in the hardware section) that had sticky backing. Put new pads on all of the door/drawer corners and voila! No more rattles! ;D . Cost ... about $2
The large TV mounted over the center of the front also rattled on bad roads. I cut a carpet scrap and put it underneath and along the sides (only at the front) of the cabinet enclosure - stopped that noise too. Cost - nil
I went to Lowes and bought a 'cheap' pull down shade and had it cut to 18". I then mounted it under the front curtains beside the driver/passenger seats (behind the valence). Now, when the sun shines in, we can pull the shade down an appropriate amount so we don't get cooked to a crisp. I mounted them so that the driver's view to the outside mirrors can't be blocked by the pulled down shade. Cost - about $10
I added similar pull down shades behind the valences in the bedroom - when we end up with a street light shining in the window, we can pull the shade - it still allows air to come through the window if they're open. (We have day/night 'waffle' shades, but they are often not enough.) Cost - about $25
The treadle for my air brakes was at a bad angle for my short stature - I had to tip my toe WAY too far to suit me and had difficulty getting real force if needed for hard braking. After searching in vain for a way to adjust the angle of the pedal, I cut a short section of 2 x 4 to an appropriate shape and screwed it to the pedal to get the angle I wanted. Cost ... zero for scrap 2 x 4 (some day I'll paint it and make it look nice <g>)
I also bought a small foot switch (ordered it online for about $6) and mounted it on top of the 2 x 4 mentioned above (after reshaping the block again <G>). I routed the normally open output of the switch (closed on activation) in series with the Xtarder switch on the dash. Now, when I let off the 'gas' pedal, the Xtarder doesn't automatically immediately kick in ... if I WANT the Xtarder, all I have to do is rest my foot on the switch sitting on top of the brake pedal - when I NEED the Xtarder under heavy braking, it's ALWAYS on since it gets activated when I step on the brake. This replaces the $85 'kit' that allows you to coast with the Xtarder switch in the on position. It also took about 20 minutes to install instead of the couple of hours to install the kit. If I turn the Xtarder switch OFF, the foot switch does nothing.
Added electric compartment door locks. I ordered the locking mechanisms from Parts Express and 'adapted' them to activate the lock. I added a DPDT momentary switch below the regular light switches by the entry door. I found some 'hot 12Volts' and wired the switch to activate Plus/Minus in one position and Minus/Plus in the other and routed to all compartment doors. Now I can lock or unlock the doors as I go in/out of the RV. Actually, I only have locks on the large doors - I have not yet been able to figure out a simple way to mount the (relatively large) activator on the small doors so that it can control the lock. It still takes care of MOST of the doors. Cost <$100 plus a few hours of work spent mostly figuring out HOW to mount the activators.
Install small 12v (computer cooling type) fan in refer - punched 2 small holes in bottom of fins and used zip ties to attach fan to bottom blowing up. Connected power to hot side of interior light so it stays on any time the refer is turned on. Cost ... about $9.
Some of these are bit more complex than others ..
Steve