Plaid Cymru has defended its Welsh assembly election spending plans after claims from other parties that their sums do not add up.
Plaid says its spending is based on Chancellor Gordon Brown's figures
Labour accused Plaid of "sci-fi politics", and Liberal Democrats said nationalists were on "Planet Plaid".
Conservatives said Plaid were "playing fast and loose with public finances".
But Plaid leader Ieuan Wyn Jones said his party's plans were realistic and affordable and accused his rivals of lacking vision and ambition.
Debate focused on Plaid's financial proposals after attacks from both Labour and the Lib Dems.
However, Plaid's leader accused Labour of "stifling wealth creation in Wales," and urged the other parties to back its policy of cutting business tax.
Mr Jones said his party wanted "to create a prosperous Wales where the government helps businesses flourish, to create skilled jobs and to boost the Welsh economy - especially in our deprived areas."
He accused Labour of creating "a bewildering array of bureaucratic and tactical initiatives rather than helping businesses".
Mr Jones accepted that Labour proposals to offer support would help some businesses.
But he added: "Redirecting some of that money into tax cuts for business would be far more effective, and help the Welsh economy in the long term.
"Plaid's proposals are realistic and affordable from within the assembly's grant and based on (Chancellor) Gordon's Brown's own figures.
"None of the other parties has such ambitious plans to transform Wales using the money already available to us."
Core public services
Labour claimed Plaid's ideas, including free laptops for schoolchildren and £5,000 grants for first-time homebuyers, were "not of this planet" because they were not possible "without freezing the wages of public sector workers and raiding the budgets of core public services."
Plaid Cymru wants to offer grants to first-time homebuyers
Labour alleged that if Plaid's manifesto was put into practice, it would mean wages would be frozen for all public sector workers, and reversals in growth in spending in such areas as the NHS and education.
Rhodri Morgan, Welsh Labour's leader, said: "This is sci-fi politics from the nationalists.
"Almost every week we have a new outlandish spending commitment, each time making their claims to be a serious party of government seem all the less credible."
"These are spending promises not of this planet.
"These are policies, Ieuan, but not as we know it. This shoddy and irresponsible wish-list would lead Wales into a crazy nationalist odyssey, a nation in such a shambles by 2011 that the institution of devolution would be a laughing stock."
Lib Dems adopted a similar space theme, with their finance spokesperson Jenny Randerson claiming that while "some planets are zero gravity, it seems Planet Plaid has zero inflation."
Ms Randerson said Plaid proposals did not take account pay increases in the health and education services.
"It can only possibly stack up if they freeze the budgets of schools, hospitals and other front-line services," she said.
"So while they want to give away free laptops, their spending plans don't cover inflationary rises in the costs of education essentials.
"That means they've ignored items such as textbooks, science and sports equipment and the condition of school buildings."
Conservative assembly group leader Nick Bourne said: "Plaid Cymru has written the longest and most expensive wish list in Welsh political history.
"When they unveiled their gimmicks and giveaways they kept their fingers crossed hoping that their sums added up. The people of Wales expect political parties to behave responsibly when it comes to spending taxpayers' money.
"They have had none of that from Plaid Cymru who are playing fast and loose with public finances."