I am in market vs i am at market

Some examples from the web:

• I am in the market for a backup mistress.
• I am not in the market for a one-dollar solid gold watch.
• Here I am in particular thinking about market practices.
• In that respect, although I am in favour of internal market regulation, I believe that the exceptional nature of the crisis justifies exceptional countermeasures.
• However, I would like to say I am in favour of retaining partial intervention in agricultural markets in difficult is not inconsistent with free market principles.
• I am all for the free market and can support any proposal that is market-orientated.
• I am at an extravagant flea market with Mark Ruffalo.
• I Am Not Officially Back On The Market.
• I am in favour of the sugar market being self-supporting.
• Finally, I am concerned that open markets and global integration are becoming a substitute for development policies.
• I am greatly in favour of opening up this fossilised market.
• Mr President, I am the European Parliament's rapporteur on the market abuse directive.
• I am referring to the regulation of the public markets and to subsidies.
• I am talking about labour market and pension reforms.
• I am in favour of unrestricted trade in waste within the common market.
• I am currently preparing a report on the regulation concerning the introduction of construction products to the market.
• Secondly, I am apprehensive about the proposal to introduce a prior market test conducted by an independent supervisor.
• Now I am all for free markets; protectionism does not work.
• I am going to highlight one objective: the internal market.
• Obviously, I am not saying we are already operating in such a market.

Some examples from the web:

• I am at an extravagant flea market with Mark Ruffalo.
• Investees will receive equity financing from private investors at market conditions.
• GDP is valued at market prices.
• Portfolio investment transactions and positions are valued at market prices.
• 6. Costs must be assessed at market prices.
• My husband is at market on business concerning you.
• Germany claims that both measures were provided at market conditions.
• Such contributions shall be calculated at market rates.
• These syndicates concentrated on selling chicory at markets further afield in Belgium, and abroad.
• Personnel handling animals at markets would have to receive the necessary training.
• The willing seller is motivated to sell the investment property at market terms for the best price obtainable.
• Gross national income at market prices 15.
• Average hourly compensations in US dollars- evaluated at market exchange rates for production workers in manufacturing in 2002.
• In the morning, at market opening.
• If delivery does take place, the purchase or sale entry shall be made at market price. 4.
• both translated at market foreign exchange rate
• Costs associated with the destruction of contaminated equipment, at market value.
• These goods should be measured at market value on an f.o.b. basis.
• Upon request, user rights had to be granted at market rates.
• General merchandise should be measured at market value on a free on board (FOB) basis.