Lets cover some of the markets on the Mainland Penang. Mainland Penang covers Seberang Prai Utara (North), Seberang Perai Tengah (Centre) and Seberang Perai Selatan (South).
Seberang Jaya Market
This is one of my favourite markets. Prices are reasonable, and the folks friendly. What I like most about this place? The morning food stalls. You can get a variety of food here, from Roti Canai, Nasi Lemak, Roti Jala, Curry Mee, Tosai, Idli, and so on. In fact I notice that there are more people in the food court then in the market. You can get your normal vegies, fruits, egg, chicken and beef meat. Don't think they have mutton here.Parking, there is a main parking before and after the market, you can also park along the roadside. The morning breakfast stalls are before the market, just follow the crowd.
Bukit Mertajam (BM) Market
This is a pretty large market. I haven't really spent much time here, but you should be able to get nearly everything you want. Parking is along side the road, and also there are some parking areas along the main road.
Chai Leng Park Market
This market is located in the housing area of Chai Leng Park. You can get all your vegies and fruits here.
Market Sama Gagah
Is market according to my friend is a market with kampung prices. i.e the prices are rather cheap, especially for the breakfast. I haven't got a chance to head here, but sure am looking forward to the breakfast and marketing here. The map link above my not be 100% exact as its not available on the online maps.
Market Orang Kaya (Rich Men's Market)
I'm not sure sure what the name of this market really is, but even in Wikimapia it says market orang kaya. This is an evening market, you can probably go there 4pm onwards, but after 6.30pm, nothing much is left. You can find vegies, fruits, and fish here. It is mean mostly for the working crowd that can stop by after work before they get home.
As usual, there are many more markets on Penang mainland, which I myself am not familiar with.