Hi Julie, Let me take a stab at this... In terms of audited statements, one of my client among other activities runs a food bank ... their audited statement includes over 1 million in in-kind contributions or about 1/4 of their budget. The auditor's notes provide details on the in-kind total. The notes also states that the # doesn't include volunteer hours, but estimates the total in the notes.
When creating grant project budgets I include estimates of in-kind. For volunteers you can use the Volunteer Sector #, currently $19.51 an hour. For other items, its best guess backed up with justification (like last years totals.) If the project budget is limited (no space) I include the info. in a footnote and discuss these significant resources in the narrative.