I made this handy chart for myself because I found myself calculating experience costs ahead of time while planning skills for my characters, so I thought I'd share.
To know how much XP you'll need to get to where you want to be from where you are, simply subtract your rank's total from your goal's total. For example, if I purchased rank 25 in a skill in character creation and I wanted to know how much XP I should set aside to practice it up to 61 (Grandmaster), I'd subtract 2700 from 12100. So, 9400 XP.
(The formatting is a bit off because tabs don't work on the forums. Oh well.)
Level Cost Total Rank
1 100 100 Incapable
2 100 200
3 100 300
4 100 400 Inept
5 100 500
6 100 600
7 100 700
8 100 800 Unskilled
9 100 900
10 100 1000
11 100 1100
12 100 1200 Capable
13 100 1300
14 100 1400
15 100 1500
16 100 1600 Competant
17 100 1700
18 100 1800
19 100 1900
20 100 2000 Proficient
21 100 2100
22 100 2200
23 100 2300
24 200 2500 Adept
25 200 2700
26 200 2900
27 200 3100
28 200 3300
29 200 3500
30 200 3700
31 200 3900
32 200 4100
33 200 4300
34 200 4500
35 200 4700
36 200 4900
37 200 5100
38 200 5300
39 200 5500
40 200 5700
41 300 6000 Master
42 300 6300
43 300 6600
44 300 6900
45 300 7200
46 300 7500
47 300 7800
48 300 8100
49 300 8400
50 300 8700
51 300 9000
52 300 9300
53 300 9600
54 300 9900
55 300 10200
56 300 10500
57 300 10800
58 300 11100
59 300 11400
60 300 11700
61 400 12100 Grandmaster
62 400 12500
63 400 12900
64 400 13300
65 400 13700
66 400 14100
67 400 14500
68 400 14900
69 400 15300
70 400 15700
71 400 16100
72 400 16500
73 400 17900
74 400 18300
75 400 18700