A 10g reef? I am looking into setting up a simple size tank so here is what I have...
The tank (already got)
Lights - par 38 led $80 dimmable
Rock/sand $80
Powerhead/s $60
Because I have a 55g saltwater I already have test kits, a refractometer and all the little bits and bobs, nets, meds, buckets, magnets etc. but that's stuff could set you back another $100 - $150 easy. (My mag float was $100 alone!)
If you don't have already an ro-di unit for making water, for a reef it is necessary IMO. They can be around $150. I am considering going filter less on mine, but if this is your first saltwater that may not suit you. My biggest concern is maintenance, a lot can go wrong in a small tank really quickly and evaporation, top offs daily. Hope that helps!