cost of this magic item? (3.5)

[EvulOne]

I'm not very good with math and especially the magic item creation lists. I have a rogue who wants a +1 Shortbow that can cause blindness (per the 2nd level wizard spell) with a shot from an arrow. I'd prefer it to be able to be used at least 3/day. Is there anyone who's math savvy that can figure it out for me?

[InvisibleBison]

A +1 shortbow costs 2,330 gp.

A use-activated item of blindess with 3 uses per day would cost 3,600 gp (spell level 2 * caster level 3 * 2,000 base * .5 for duration longer than 24 hours / 5/3 for 3 charges/day).

Adding the two together causes the second to increase in price by 50%, so the final cost would be 7,330 gp.