Hi Linda,
A tricky one as everyone has different indulgences! I took £750 (bank statement) in local currency which gave me about £50.00 a day (including gratuities) and recall I had quite a bit left over.... (£2/300 as I recall)
Your main daily spending will be lunches & dinners and you could eat at a reasonable price wherever we went. I am not what you might call a drinker so never had more than a couple of beers in an evening- tastes here can of course have an impact on your restaurant bill.
As for souvenirs then in most places prices are "negotiable" & I would rather come back with a few quality items (which I did) rather than a load of "tat".
I had sterling to tip the TM but we had a lovely lady by the name of Kim who lives in San Francisco so I tipped her in local currency as she does a lot of Mexican trips & sterling would probably not be a lot of use to her!
On the whole it is not expensive and my indulgences were some good quality souvenirs - and as a photographer a whole load of photographs.
Ian