A standard package of tuition fees and bursaries should be introduced for UK universities, an adviser to the Welsh Assembly Government has said.
Professor Teresa Rees said the different rates for a university education across the UK were "barking".
She said there should be a strategic decision on fees charged and bursaries available for all students.
The Department for Business, Innovation and Skills said higher education was a devolved matter.
Prof Rees has led two commissions on higher education for the Welsh assembly and is in favour of devolution.
However, the former pro-vice-chancellor of Cardiff University and professor in the School of Social Sciences at the university, said the current system of different fees across the UK is too complex.
"At the moment it's unbelievably complicated - if you're a student from Northern Ireland and you want to study in England, you know, what you'd be eligible for would be very different from an English student wanting to study in Scotland.
"I mean, this isn't really very grown-up, strategic thinking about higher education in the UK, I think it's barking - we do have to remember cross-border flows.
"And this affects Wales more than any other country because say, for argument's sake, half the students from Wales go to English universities and half the students in Wales are from England, that means that any kind of arrangement regarding carrots and sticks in terms of fees can affect that cross-border flow very dramatically and very quickly, and this isn't very strategic."
Prof Rees said a student from a less privileged home in Wales would do well to take the subsidy on offer from the Welsh Assembly Government, then apply to an English university offering generous bursaries.
But a student from a poorer home in England would not be advised to study in Wales, because he or she would "pick up from neither place".
Prof Rees said the problem of cross-border flow within the UK was demonstrated when the UK government brought in "golden hellos" to help with teacher shortages in England.
This led to a problem in Wales, as newly-qualified teachers headed over the border to pick up the extra cash on offer.
She believes there needs to be a UK-wide agreement on what universities will charge in future if they are to survive and prosper.
A spokesperson for the Department for Business, Innovation and Skills said: "Higher education is a devolved matter but the administrations are in regular contact to make sure we understand each others' policies and the implications of them."
English and Welsh universities will be able to charge up to £9,000 from 2012, though Welsh students will be subsidised wherever they study.
In Northern Ireland fees could rise to £6,000.
Three out of the four main political parties in Scotland have ruled out charging Scottish students for their courses.
But Scotland's universities have to plug a £155m funding gap - so whichever party gains power after elections on 5 May will have to change the system or make cuts elsewhere.