Anyway, why do you think you should pay for repairs or other things out of pocket before escrow closes? Why would you invest in someone else's property just to get their business. You'll be out that money whether the property sells. What if you pay for repairs or staging and then they cancel the listing agreement prematurely. Of course you can make the cancellation contingent upon them paying your out-of-pocket expenses, but I can guarantee you that they won't be happy if you actually follow through with it.
My suggestion to you would be that you offer to pay for certain things at the close of escrow (I have offered to pay for the pre-inspection termite report at COE or the appraisal), but I won't pay for those items if escrow does not close. By offering to pay you also make it look like you are desperate to get their listing.
My advise is, if you feel you have to make a contribution, do it when escrow closes and you have a commission to pay it from. You'll have plenty of opportunity to spend your money during the listing period because you'll have to spend at least some money on marketing the property. You need to lead by revenue (i.e., don't spend money that you have not yet earned). I would highly recommend that you read the Millionaire Real Estate Agent (co-authored by Gary Keller, co-founder of Keller Williams Realty).
We do similar things with our sellers and here is the concern and solution that we came up with:
We as listing brokers are out money on the front end of taking any listing before we offer the seller incentives of this nature. If for any reason (difficult seller included) we don't sell the listing how do we recoup this additional loss? To overcome this hurdle we offer reimbursement of these incentives if the deal closes.
In regards to violations, law, ethics etc..., you'll need to talk to your attorney to ensure you don't open yourself up to liability.
With that said, two things I do offer if they don't already have it - sellers home warranty coverage while the property is listed with me (you only pay at close of escrow), and the initial staging consultation if i feel they will get the points accross better than I. Those are just part of my standard services so we can help sell the house.
If you upfront costs and the proeprty does not sell you could be out of pocket money with no reimbursement. If allowable in you state you might be able to offer a reimbursement at close of escrow so you are not out of pocket.