They provide a recommended donation, can get tickets without a donation or for less than recommended amount. You can get tickets online bebfore you get there.
Free
When I went in June 2018 the suggested donation was $25 but they were cool with my group of 5 paying 25 total.
$15 adult 12 and under $10. Yes you can.
They sell oils in the gift shop.
It suggested that you give 15 but you can give any amount
It was a "suggested donation of $15" (which is cheap for DC!), But assuming you meant "annointing" oil???? Not sure about that.
I went with the AARP. So everything was in the fee I paid, so not sure. And not sure about the oil
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