Second Birthday Invitation Verses Birthday Party?

Birthday Party? - second birthday invitation verses

My main concern is 8 At the end of March and is starting the second year. I'm looking for creative ideas for birthday party costs. Last year we had the bowling alley, but because it is so expensive that only some children can invite into the school because her cousins all went well. Then an idea? She wants to invite about 20 children this year (I know, do not get all of you and I know if I can do to reduce the list), but I think it would be fun to have a big birthday party with all his friends and relatives, but I am a single mother and full-time students and have a big budget. Such a creative idea for some who may invitations to birthday parties? Thanks in advance!
PS How old is the invitation sent? 2 weeks? And even when I have more invitations in the school and handed them over to school, but felt excluded children or parents never enough. I want them to school w / her or sent to their home