This is an auction near to me:
http://www.ams.usda.gov/mnreports/ln_ls322.txt
Here is a snippet of the report:
Slaughter Lambs Wooled & Shorn Choice and Prime 2-3
Head Wt Range Avg Wt Price Range Avg Price
30 40-50 44 290.00-300.00 298.29
101 50-60 54 300.00-330.00 308.05
7 50-60 54 275.00 275.00 Hair Sheep
8 60-70 62 290.00-315.00 302.10
17 70-80 72 275.00-290.00 282.89 Hair Sheep
21 80-90 82 255.00-270.00 257.99
34 90-110 99 228.00-250.00 235.75
58 110-130 117 176.00-235.00 190.93
Slaughter Lambs Wooled & Shorn Choice 2-3
Head Wt Range Avg Wt Price Range Avg Price
9 40-50 48 270.00 270.00
19 40-50 44 275.00-297.00 282.97 Hair Sheep
41 40-50 47 260.00-290.00 280.87
10 50-60 52 230.00-250.00 241.54 Hair Sheep
6 60-70 63 290.00 290.00
13 60-70 60 297.00 297.00 Hair Sheep
71 70-80 75 247.00-275.00 265.48
3 70-80 70 280.00 280.00 Hair Sheep
42 80-90 83 232.00-240.00 234.66
21 80-90 87 235.00-265.00 257.84 Hair Sheep
111 90-110 95 190.00-221.00 209.69
35 90-110 100 210.00-236.00 222.29 Hair Sheep
85 110-130 118 164.00-190.00 171.19
4 110-130 121 170.00 170.00 Hair Sheep
22 130-150 137 157.00-170.00 164.58
12 150-200 155 120.00-150.00 147.42
4 150-200 151 127.00 127.00 Hair Sheep
Slaughter Lambs Wooled & Shorn Good 1-2
Head Wt Range Avg Wt Price Range Avg Price
5 70-80 76 137.00 137.00 Hair Sheep
8 80-90 83 140.00 140.00
22 90-110 107 180.00-200.00 186.39 Hair Sheep
31 110-130 127 92.00-102.00 94.78
5 110-130 113 100.00 100.00 Hair Sheep
51 130-150 141 150.00-166.00 161.70
8 150-200 162 104.00-112.00 107.94
Slaughter Lambs Wooled & Shorn Good 1-3
Head Wt Range Avg Wt Price Range Avg Price
7 90-110 101 110.00-150.00 127.43 Hair Sheep
11 110-130 112 192.00 192.00 Hair Sheep
17 130-150 134 100.00-105.00 102.39
5 150-200 162 118.00 118.00
4 150-200 173 100.00 100.00 Hair Sheep
Slaughter Ewes Good 2-3
Head Wt Range Avg Wt Price Range Avg Price
66 120-160 137 82.00-117.00 101.55
25 160-200 168 102.00-104.00 102.91
17 200-300 208 80.00-104.00 94.74
Slaughter Ewes Utility 1-3
Head Wt Range Avg Wt Price Range Avg Price
15 120-160 133 92.00-107.00 99.32
15 160-200 176 94.00-100.00 96.88
7 200-300 223 76.00-94.00 86.13
Slaughter Ewes Cull 1-2
Head Wt Range Avg Wt Price Range Avg Price
14 120-160 152 76.00 76.00
38 160-200 172 70.00-78.00 72.04
Slaughter Bucks
Head Wt Range Avg Wt Price Range Avg Price
25 120-160 140 76.00-98.00 86.92
1 120-160 140 117.00 117.00 Hair Sheep
29 160-200 172 70.00-130.00 100.75
16 200-300 228 68.00-102.00 84.45
"Head" refers to how many were sold.
"Wt Range" refers to the weight range of the number of animals listed.
"Avg Wt" refers to the average weight of the number of animals listed.
"Price Range" refers to the price range of the number of animals listed.
"Avg Price" refers to the average price of the number of animals listed.
Note that price is listed per cwt (hundred weight, 100 lbs), so where it says 120, it actually means $1.20/lb.
Now, let's just say you have a lamb that is 74 lbs that you want to sell. To find how much you could sell the lamb for, go to the weight range where it says 70-80. In Good, Choice, and Choice and Prime (carcass grades), you have four options listed for the weight range.
Here they are:
Slaughter Lambs Wooled & Shorn Choice and Prime 2-3
Head Wt Range Avg Wt Price Range Avg Price
17 70-80 72 275.00-290.00 282.89 Hair Sheep
Slaughter Lambs Wooled & Shorn Choice 2-3
Head Wt Range Avg Wt Price Range Avg Price
71 70-80 75 247.00-275.00 265.48
3 70-80 70 280.00 280.00 Hair Sheep
Slaughter Lambs Wooled & Shorn Good 1-2
Head Wt Range Avg Wt Price Range Avg Price
5 70-80 76 137.00 137.00 Hair Sheep
It looks like hair sheep sell for a little bit more than non-specified hair sheep.
Your lamb is 74 lbs, so you would look at the average weight of 75 (under choice) and get the price per pound of $2.6548, making your lamb worth about $196.46. Ideally, you would match it up to the carcass grade, which of course depends on breed, genetics, and feeding. Meat type breeds will almost always be found towards the top, depending on how they're fed. Lean hair breeds (barbados and possibly St. Croix) and smaller thin boned breeds (Shetland, maybe Icelandic??) will find it hard to grade that high unless they're fed well to put some muscle and fat on.
Here's information on grades:
http://www.vdacs.virginia.gov/livestock/lambcarcass.shtml
Let me know if you have anymore questions.