Her visa was obtained on May 24. We submitted an invitation letter to the UK from me, payslips for about 5-6 months from her job, planned travel dates to the UK and a date she plans to return, and a cover letter from hereher (see here: Is there anything we could add or change to this cover letter for a UK Standard Visitor Visa?). The fact the estimated cost of trip increased after we sent the application didn't seem to affect it from what we could see but it's definitely possible the ECO was aware of this and took it into consideration.
There were no issues during the application process other than it went sent from New York, USA to Croydon, UK for administrative purposes. I think it took about 6-7 weeks to get a reply from her visa application.
She didn't travel to the UK until August 2 and she stayed until August 21 before returning to USA. On her entry to the UK she was sat aside for 15 minutes while the IO asked her to wait. He then went off alone and came back 15 minutes later before allowing her entry on her visa.