I think if you are a god parent it is nice to give the baby a little token gift that will be something nice through their early years - I have happy memories of a pretty bracelet I was allowed to wear on special occasions that had been a christening gift and also we always used the cutlery that we'd been given along with little metal plate and cup.
In fact you have just reminded me that when we were little mum always used to say that we could have them when we were older as they were 'ours' but they are really useful sizes so she still uses them . Wish you could still get little metal plates for kiddies, hey ho.
If I'm a god parent I like to give something like that or maybe a nice book if I am just a guest, usually something traditional like Beatrix Potter that will last through childhood. I know it is not obligatory but it is still nice to do.
You have just reminded me that ds1 got given a silver plated christening certificate holder. Had the wrong details engraved on the front, was from a different country so wrong size for actually holding the certificate without it being folded and really ugly to boot. I said thank you very nicely and I know they put a lot of effort into it but it just made me sad on so m any different levels that somebody thought it was a good idea (I wouldn't dream of keeping certificates for anything anywhere but a filing cabinet otherwise they would get lost), that it was a nice present, that it would need dusting, that they didn't check details before getting them engraved etc... It's now stuck at the back of a cupboard somewhere, can't even ebay or jumble shop it as it is engraved!
OP - guess if they gave money to your dd for her christening, could you not say that the amount they gave her you will put into a bank account for her or buy her a small something with (did anybody give her a book of bible stories?) and save the rest of the money? Then you can tell the PIL what you have done with the money they gave to your dd for her christening and ask them to sign the book for her to look back on in years to come.
Or did they assume that because they gave you the money for the tea they could dictate how the tea was done and thereby remove those choices from you that you would have liked? (am getting hint of this from OP) If this is the case then if she ever asks, and you are not feeling charitable towards them, you can just tell her that they bought the right to interfere in her christening tea as their gift .
Sounds like your dh should have spoken to you about it beforehand though, could you speak to him about it now and say how unhappy it has made you feel, and see if you can work out some solution? Otherwise you might find it happens time and time again when he agrees stuff with his parents before checking out with you... definitely something to be nipped in the bud!