I would ask for a detailed breakdown of costs which make up the $1000 fee:
* travelling costs
* research fee per hour
* what precisely has she found - 26 records... are they indexes, copies of original documents?
Why did she research your grandmother's side first when your priority is your grandfather's side? Did you make it clear you wanted your grandfather's research to be carried out first? Did you know she was going to visit Tarnow?
If you have doubts then inform her that she is not to carry out any further research for now. Specifically tell her not to visit Kracow.
It's difficult to say if her fees are reasonable until you have a detailed invoice.
If she is genuine she will send you a detailed breakdown of the $1000 fee and you can take things from there. Just make sure you make it clear that she is to stop researching for now.
I research in the UK mainly and give really detailed invoices for my paid work, broken down into - * hourly research fees and what precisely I have done in the number of hours I am charging for
* exact costs of each copy document I will provide, eg, 2 birth certs at £x each, 4 copy census returns at £y each
* travel costs (including train ticket and copy credit card receipt)
* any other expenses/charges
I hope this helps. Remember you are the client and you instruct the researcher. If you need any more help please say.