I agree that slot rings are technically inlaid, I wouldn't count them when adding in "inlay" value. But I would count them when adding in "ring" value. I have set prices for each item going into my cues, add that to the base price of $250 and you have your retail price.
Now, I have cues with bar bell designs, but again, would you consider that 3 inlays or 1 deco ring and 2 inlays (per bar bell)? I would personally value you the cue at 1 deco and 2 inlays (per bar bell)!
That would mean you would need a price for each ring going into the cue before even building it. I would think that slotted deco rings could range from $15-$30 per ring. That price does not include any added "inlays" to the ring after installed on the cue (dots, diamonds, etc).
What's nice about the custom cue market... every cue is different and every cuemaker has the right to charge what he/she feels like charging.
Just my .02,
Zim