A snippet from a libertarian standpoint:
The government can create programs which lose money every month - programs which are constantly "in the red". It will simply be subsidized through tax money. An example of this is the postal service. Universal healthcare would be MUCH more costly than an institution such as the postal service though. On a side note, I've heard that the government has tried to sell the postal service several times in the past, but nobody will buy it because it CANNOT be profitable because there needs to be a staffed post office in EVERY podunk town.
On top of that, a government run healthcare system would create large bureaucracies... because the government needs to scrutinize and formalize everything. Business that stay in business are much more efficient - they need to be to stay afloat! Anyway, where does the money to subsidize the new government system come from? It has to come from somewhere. Aside from simply printing more money, which causes inflation, it comes from taxing the rich and businesses. The business must stay in business and maintain profits, so they increase the prices of their products, and consumers have to pay more for things as a result. This decreases the amount of goods bought because the goods are at higher prices and people can't go on buying just as much stuff if the prices of goods has gone up. This strain on the amount of goods purchased by average consumer can drive small companies out of business and can result in less profitability from larger businesses, hurting the economy in general.
Hope that gave you some ideas at least!