Most pumps are pretty easy to swap out. As it sounds like your main water source, I would think you would want one of the better quality pumps like pehaps a Goulds pump.

fwiw;
I had some additional shallow wells installed many years ago by a three man shop, knowledgeable, did a good job, old owner explained in detail our area water table and what's down there as his young grandson_helper and friend did all the work - typical been in business since 1930's old time local pump&well contracor - he quoted a small fortune for a new one hp pump and its installation.
At the time I figured he used a typical 3x markup on his material costs as the maybe one labor hour for the two lads didnt otherwise justify price.

I am flying blind here because you haven't given any real information so that I can see what your pump looks like but here goes.

New pumps with a cracked housing can be repaired easily. Look at the pump, find the make and model, call up the manufacturer and find out how many companies in your area are authorized dealers. Then call three of them and get a quote for the new housing just to make sure that you aren't getting screwed.

Order the new housing from whomever will sell it cheapest. Changing the housing will require a pair of decent pipe wrenches to handle the plumbing fittings and likely a box-end wrench to remove the bolts holding the damaged front housing to the rear section. As long as you haven't run this pump with it being dry, the ceramic seal should be ok. Water inside the housing lubricates and cools the ceramic seal. With no water in the housing, it only takes a minute or so of run-time to ruin that seal.

To throw away a new pump over a cracked housing seems rather foolish unless there is more to this than what you have explained so far. Those guys that want to sell you a new pump will be happy to take your old one, put a new housing on it and then sell it to someone else for a slight discount.

Thanks for replies so far. I got the name and model off the unit - it is a Flint & Walling (F&W) CJ101B151. Looking up the company's site revealed a list price of over $1100! One retailer shows it for about $920.

According to company literature these prods are quite modular and parts can be replaced without too much trouble. I did try to contact them but no luck as they were apparently too busy; will try again tomorrow.

I should say that the serviceman who came out did turn on the pump, noticed a small leak (no squirting, just a trickle at the rate of perhaps a cup of water every couple of minutes) and did not attempt to run the sprinklers, saying "you'll never get this one to work". I wonder if this size of crack/leak is almost inconsequential and it is worth a try to run the system.

This is a sprinkler pump BTW and not essential for everyday living (for me at least). But as it is the first home we have owned with sprinklers and the water for it is free (from the lake) I sure would like to use it. Lots of grass to cover; I would guess around 1/2 acre total.

You have a two-stage centrifugal pump. As such, it has two impellers instead of the usual one impeller. It also has multiple castings that form part of the pump housing. The leak could be in any one of these castings. You will have to determine exactly where the water is coming from before you can come up with a plan for repair.

More than likely, all the housing parts are cast iron and if the crack is minor, then you could remove the housing from the pump and have it welded by someone in the welding business who KNOWS how to weld cast iron properly. I suggest that option in case the price for the part turns out to be obscene.

It the part is reasonable in price, then just order it and repair this pump yourself. If you go to the link below and click on "repair parts", you will find a PDF that shows an exploded diagram of your pump with all the part numbers. You might need item 3 or 9 or 10 if the leak is due to a break in the casting.

Here is a link that might be useful: Pump